diff --git a/docs/book/src/clusterctl/commands/alpha-topology-plan.md b/docs/book/src/clusterctl/commands/alpha-topology-plan.md
index cc5dd5d779ac..a73ab8db1bd6 100644
--- a/docs/book/src/clusterctl/commands/alpha-topology-plan.md
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@@ -1,3 +1,438 @@
 # clusterctl alpha topology plan
 
-**Under Construction**
+The `clusterctl alpha topology plan` command can be used to get a plan of how a Cluster topology evolves given
+file(s) containing resources to be applied to a Cluster.
+
+The input file(s) could contain a new/modified Cluster, a new/modified ClusterClass and/or new/modified templates, 
+depending on the use case you are going to plan for (see more details below).
+
+The topology plan output would provide details about objects that will be created, updated and deleted of a target cluster; 
+If instead the command detects that the change impacts many Clusters, the users will be required to select one to focus on (see flags below).
+
+```shell
+clusterctl alpha topology plan -f input.yaml -o output/
+```
+
+<aside class="note">
+
+<h1>Running without a management cluster</h1>
+
+This command can be used with or without a management cluster. In case the command is used without a management cluster 
+the input should have all the objects needed.
+
+</aside>
+
+## Example use cases
+ 
+### Designing a new ClusterClass
+
+When designing a new ClusterClass users might want to preview the Cluster generated using such ClusterClass. 
+The `clusterctl alpha topology plan command` can be used to do so:
+
+```shell
+clusterctl alpha topology plan -f example-cluster-class.yaml -f example-cluster.yaml -o output/
+```
+
+`example-cluster-class.yaml` holds the definitions of the ClusterClass and all the associated templates. 
+<details>
+<summary>View <code>example-cluster-class.yaml</code></summary>
+
+```yaml
+apiVersion: cluster.x-k8s.io/v1beta1
+kind: ClusterClass
+metadata:
+  name: example-cluster-class
+  namespace: default
+spec:
+  controlPlane:
+    ref:
+      apiVersion: controlplane.cluster.x-k8s.io/v1beta1
+      kind: KubeadmControlPlaneTemplate
+      name: example-cluster-control-plane
+      namespace: default
+    machineInfrastructure:
+      ref:
+        kind: DockerMachineTemplate
+        apiVersion: infrastructure.cluster.x-k8s.io/v1beta1
+        name: "example-cluster-control-plane"
+        namespace: default
+  infrastructure:
+    ref:
+      apiVersion: infrastructure.cluster.x-k8s.io/v1beta1
+      kind: DockerClusterTemplate
+      name: example-cluster
+      namespace: default
+  workers:
+    machineDeployments:
+    - class: "default-worker"
+      template:
+        bootstrap:
+          ref:
+            apiVersion: bootstrap.cluster.x-k8s.io/v1beta1
+            kind: KubeadmConfigTemplate
+            name: example-docker-worker-bootstraptemplate
+        infrastructure:
+          ref:
+            apiVersion: infrastructure.cluster.x-k8s.io/v1beta1
+            kind: DockerMachineTemplate
+            name: example-docker-worker-machinetemplate
+---
+apiVersion: infrastructure.cluster.x-k8s.io/v1beta1
+kind: DockerClusterTemplate
+metadata:
+  name: example-cluster
+  namespace: default
+spec:
+  template:
+    spec: {}
+---
+kind: KubeadmControlPlaneTemplate
+apiVersion: controlplane.cluster.x-k8s.io/v1beta1
+metadata:
+  name: "example-cluster-control-plane"
+  namespace: default
+spec:
+  template:
+    spec:
+      machineTemplate:
+        nodeDrainTimeout: 1s
+      kubeadmConfigSpec:
+        clusterConfiguration:
+          controllerManager:
+            extraArgs: { enable-hostpath-provisioner: 'true' }
+          apiServer:
+            certSANs: [ localhost, 127.0.0.1 ]
+        initConfiguration:
+          nodeRegistration:
+            criSocket: /var/run/containerd/containerd.sock
+            kubeletExtraArgs:
+              cgroup-driver: cgroupfs
+              eviction-hard: 'nodefs.available<0%,nodefs.inodesFree<0%,imagefs.available<0%'
+        joinConfiguration:
+          nodeRegistration:
+            criSocket: /var/run/containerd/containerd.sock
+            kubeletExtraArgs:
+              cgroup-driver: cgroupfs
+              eviction-hard: 'nodefs.available<0%,nodefs.inodesFree<0%,imagefs.available<0%'
+---
+apiVersion: infrastructure.cluster.x-k8s.io/v1beta1
+kind: DockerMachineTemplate
+metadata:
+  name: "example-cluster-control-plane"
+  namespace: default
+spec:
+  template:
+    spec:
+      extraMounts:
+      - containerPath: "/var/run/docker.sock"
+        hostPath: "/var/run/docker.sock"
+---
+apiVersion: infrastructure.cluster.x-k8s.io/v1beta1
+kind: DockerMachineTemplate
+metadata:
+  name: "example-docker-worker-machinetemplate"
+  namespace: default
+spec:
+  template:
+    spec: {}
+---
+apiVersion: bootstrap.cluster.x-k8s.io/v1beta1
+kind: KubeadmConfigTemplate
+metadata:
+  name: "example-docker-worker-bootstraptemplate"
+  namespace: default
+spec:
+  template:
+    spec:
+      joinConfiguration:
+        nodeRegistration:
+          kubeletExtraArgs:
+            cgroup-driver: cgroupfs
+            eviction-hard: 'nodefs.available<0%,nodefs.inodesFree<0%,imagefs.available<0%'
+```
+
+</details>
+
+`example-cluster.yaml` holds the definition of `example-cluster` Cluster.
+<details>
+<summary>View <code>example-cluster.yaml</code></summary>
+
+```yaml
+apiVersion: cluster.x-k8s.io/v1beta1
+kind: Cluster
+metadata:
+  name: "example-cluster"
+  namespace: "default"
+  labels:
+    cni: kindnet
+spec:
+  clusterNetwork:
+    services:
+      cidrBlocks: ["10.128.0.0/12"]
+    pods:
+      cidrBlocks: ["192.168.0.0/16"]
+    serviceDomain: "cluster.local"
+  topology:
+    class: example-cluster-class
+    version: v1.21.2
+    controlPlane:
+      metadata: {}
+      replicas: 1
+    workers:
+      machineDeployments:
+      - class: "default-worker"
+        name: "md-0"
+        replicas: 1
+```
+
+</details>
+
+Produces an output similar to this:
+```shell
+The following ClusterClasses will be affected by the changes:
+ ＊ default/example-cluster-class
+
+The following Clusters will be affected by the changes:
+ ＊ default/example-cluster
+
+Changes for Cluster "default/example-cluster": 
+
+  NAMESPACE  KIND                   NAME                                  ACTION    
+  default    DockerCluster          example-cluster-rnx2q                 created   
+  default    DockerMachineTemplate  example-cluster-control-plane-dfnvz   created   
+  default    DockerMachineTemplate  example-cluster-md-0-infra-qz9qk      created   
+  default    KubeadmConfigTemplate  example-cluster-md-0-bootstrap-m29vz  created   
+  default    KubeadmControlPlane    example-cluster-b2lhc                 created   
+  default    MachineDeployment      example-cluster-md-0-pqscg            created   
+  default    Secret                 example-cluster-shim                  created   
+  default    Cluster                example-cluster                       modified  
+
+Created objects are written to directory "output/created"
+Modified objects are written to directory "output/modified"
+```
+
+The contents of the output directory are similar to this:
+```
+output
+├── created
+│   ├── DockerCluster_default_example-cluster-rnx2q.yaml
+│   ├── DockerMachineTemplate_default_example-cluster-control-plane-dfnvz.yaml
+│   ├── DockerMachineTemplate_default_example-cluster-md-0-infra-qz9qk.yaml
+│   ├── KubeadmConfigTemplate_default_example-cluster-md-0-bootstrap-m29vz.yaml
+│   ├── KubeadmControlPlane_default_example-cluster-b2lhc.yaml
+│   ├── MachineDeployment_default_example-cluster-md-0-pqscg.yaml
+│   └── Secret_default_example-cluster-shim.yaml
+└── modified
+    ├── Cluster_default_example-cluster.diff
+    ├── Cluster_default_example-cluster.jsonpatch
+    ├── Cluster_default_example-cluster.modified.yaml
+    └── Cluster_default_example-cluster.original.yaml
+```
+
+### Plan changes to Cluster topology
+
+When making changes to a Cluster topology the `clusterctl alpha topology plan` can be used to analyse how the underlying objects will be affected.
+
+```shell
+clusterctl alpha topology plan -f modified-example-cluster.yaml -o output/
+```
+
+The `modified-example-cluster.yaml` scales up the control plane to 3 replicas and adds additional labels to the machine deployment.
+<details>
+<summary>View <code>modified-example-cluster.yaml</code></summary>
+
+```yaml
+apiVersion: cluster.x-k8s.io/v1beta1
+kind: Cluster
+metadata:
+  name: "example-cluster"
+  namespace: default
+  labels:
+    cni: kindnet
+spec:
+  clusterNetwork:
+    services:
+      cidrBlocks: ["10.128.0.0/12"]
+    pods:
+      cidrBlocks: ["192.168.0.0/16"]
+    serviceDomain: "cluster.local"
+  topology:
+    class: example-cluster-class
+    version: v1.21.2
+    controlPlane:
+      metadata: {}
+      # Scale up the control plane from 1 -> 3.
+      replicas: 3
+    workers:
+      machineDeployments:
+      - class: "default-worker"
+        # Apply additional labels.
+        metadata: 
+          labels:
+            test-label: md-0-label
+        name: "md-0"
+        replicas: 1
+```
+</details>
+
+Produces an output similar to this:
+```shell
+Detected a cluster with Cluster API installed. Will use it to fetch missing objects.
+No ClusterClasses will be affected by the changes.
+The following Clusters will be affected by the changes:
+ ＊ default/example-cluster
+
+Changes for Cluster "default/example-cluster": 
+
+  NAMESPACE  KIND                 NAME                        ACTION    
+  default    KubeadmControlPlane  example-cluster-l7kx8       modified  
+  default    MachineDeployment    example-cluster-md-0-j58ln  modified  
+
+Modified objects are written to directory "output/modified"
+```
+
+### Rebase a Cluster to a different ClusterClass
+
+The command can be used to plan if a Cluster can be successfully rebased to a different ClusterClass.
+
+Rebasing a Cluster to a compatible ClusterClass:
+```shell
+# Rebasing example-cluster to a compatible ClusterClass.
+clusterctl alpha topology plan -f example-cluster-good-rebase.yaml -o output/
+```
+
+Rebasing a Cluster to an incompatible ClusterClass:
+```shell
+# Rebasing example-cluster to an incompatible ClusterClass.
+# In this example the target ClusterClass is incompatible because it is missing 
+# a worker class that is used by the Cluster.
+clusterctl alpha topology plan -f example-cluster-bad-rebase.yaml -o output/
+```
+
+`example-cluster-bad-rebase.yaml` is rebasing the `example-cluster` Cluster to `incompatible-cluster-class` ClusterClass. In this example the `incompatible-cluster-class` is already installed in the management cluster.
+
+<details>
+<summary>View <code>example-cluster-bad-rebase.yaml</code></summary>
+
+```yaml
+apiVersion: cluster.x-k8s.io/v1beta1
+kind: Cluster
+metadata:
+  name: "example-cluster"
+  namespace: "default"
+  labels:
+    cni: kindnet
+spec:
+  clusterNetwork:
+    services:
+      cidrBlocks: ["10.128.0.0/12"]
+    pods:
+      cidrBlocks: ["192.168.0.0/16"]
+    serviceDomain: "cluster.local"
+  topology:
+    # ClusterClass is changed from 'example-cluster-class' -> 'incompatible-cluster-class' 
+    class: incompatible-cluster-class
+    version: v1.21.2
+    controlPlane:
+      metadata: {}
+      replicas: 1
+    workers:
+      machineDeployments:
+      - class: "default-worker"
+        name: "md-0"
+        replicas: 1
+```
+
+</details>
+
+Produces an output similar to:
+```shell
+Detected a cluster with Cluster API installed. Will use it to fetch missing objects.
+Error: failed defaulting and validation on input objects: failed to run defaulting and validation on Clusters: failed validation of cluster.x-k8s.io/v1beta1, Kind=Cluster default/example-cluster: Cluster.cluster.x-k8s.io "example-cluster" is invalid: spec.topology.workers.machineDeployments[0].class: Invalid value: "default-worker": MachineDeploymentClass with name "default-worker" does not exist in ClusterClass "incompatible-cluster-class"
+```
+
+### Testing the affects of changing a ClusterClass
+
+When planning for a change on a ClusterClass you might want to understand what effects the change will have on existing clusters.
+
+```shell
+clusterctl alpha topology plan -f modified-first-cluster-class.yaml -o output/
+```
+When multiple clusters are affected, only the list of Clusters and ClusterClasses is presented.
+```shell
+Detected a cluster with Cluster API installed. Will use it to fetch missing objects.
+The following ClusterClasses will be affected by the changes:
+ ＊ default/first-cluster-class
+
+The following Clusters will be affected by the changes:
+ ＊ default/first-cluster
+ ＊ default/second-cluster
+
+No target cluster identified. Use --cluster to specify a target cluster to get detailed changes.
+```
+
+To get the full list of changes for the "first-cluster":
+```shell
+clusterctl alpha topology plan -f modified-first-cluster-class.yaml -o output/ -c "first-cluster"
+```
+Output will be similar to the full summary output provided in other examples.
+
+## Reference
+
+The topology plan operation is composed of the following steps:
+* Set the namespace on objects in the input with missing namespace.
+* Run the Defaulting and Validation webhooks on the Cluster and ClusterClass objects in the input.
+* Dry run the topology reconciler on the target cluster.
+* Capture all changes observed during reconciliation.
+
+## Input
+
+### `--file`, `-f` (REQUIRED)
+ 
+The input file(s) with the target changes. Supports multiple input files. 
+
+The objects in the input should follow these rules:
+* All the objects in the input should belong to the same namespace.
+* Should not have multiple Clusters.
+* Should not have multiple ClusterClasses.
+
+<aside class="note warning">
+
+<h1>Object namespaces</h1>
+
+If some of the objects have a defined namespace and some do not, the objects are considered as belonging to different namespaces
+which is not allowed.
+
+</aside>
+
+<aside class="note warning">
+
+<h1>Defaulting and Validation</h1>
+
+All templates in the inputs should be fully valid and have all the default values set. `topology plan` will not run any defaulting 
+or validation on these objects. Defaulting and validation is only run on Cluster and ClusterClass objects.
+
+</aside>
+
+### `--output-directory`, `-o` (REQUIRED)
+
+Information about the objects that are created and updated is written to this directory.
+
+For objects that are modified the following files are written to disk:
+* Original object
+* Final object
+* JSON patch between the original and the final objects
+* Diff of the original and final objects
+
+### `--cluster`, `-c` (Optional)
+
+When multiple clusters are affected by the input, `--cluster` can be used to specify a target cluster. 
+
+If only one cluster is affected or if a Cluster is in the input it defaults as the target cluster. 
+
+### `--namespace`, `-n` (Optional)
+
+Namespace used for objects with missing namespaces in the input.
+
+If not provided, the namespace defined in kubeconfig is used. If a kubeconfig is not available the value `default` is used.
+