diff --git a/src/protections/RoomTakedown/RoomDiscovery.ts b/src/protections/RoomTakedown/RoomDiscovery.ts
new file mode 100644
index 00000000..bddbdca6
--- /dev/null
+++ b/src/protections/RoomTakedown/RoomDiscovery.ts
@@ -0,0 +1,106 @@
+// SPDX-FileCopyrightText: 2025 Gnuxie <Gnuxie@protonmail.com>
+//
+// SPDX-License-Identifier: Apache-2.0
+
+import {
+  ConstantPeriodItemBatch,
+  isError,
+  Logger,
+  SHA256RoomHashStore,
+  StandardBatcher,
+} from "matrix-protection-suite";
+import { CheckEventForSpamRequestBody } from "../../webapis/SynapseHTTPAntispam/CheckEventForSpamEndpoint";
+import { SynapseHttpAntispam } from "../../webapis/SynapseHTTPAntispam/SynapseHttpAntispam";
+import { StringRoomID } from "@the-draupnir-project/matrix-basic-types";
+import { UserMayInviteRequestBody } from "../../webapis/SynapseHTTPAntispam/UserMayInviteEndpoint";
+import { UserMayJoinRoomRequestBody } from "../../webapis/SynapseHTTPAntispam/UserMayJoinRoomEndpoint";
+
+const log = new Logger("SynapseHTTPAntispamRoomDiscovery");
+
+export interface RoomDiscovery {
+  unregisterListeners(): void;
+}
+
+export class SynapseHTTPAntispamRoomDiscovery implements RoomDiscovery {
+  private readonly discoveredRooms = new Set<StringRoomID>();
+  private readonly batcher = new StandardBatcher(
+    () =>
+      new ConstantPeriodItemBatch<StringRoomID, void>(
+        this.forwardDiscoveredBatch,
+        { waitPeriodMS: 2500 }
+      )
+  );
+  constructor(
+    private readonly synapseHTTPAntispam: SynapseHttpAntispam,
+    private readonly hashStore: SHA256RoomHashStore
+  ) {
+    synapseHTTPAntispam.checkEventForSpamHandles.registerNonBlockingHandle(
+      this.handleCheckEventForSpam
+    );
+    synapseHTTPAntispam.userMayInviteHandles.registerNonBlockingHandle(
+      this.handleUserMayInvite
+    );
+    synapseHTTPAntispam.userMayJoinRoomHandles.registerNonBlockingHandle(
+      this.handleUserMayJoin
+    );
+  }
+
+  private readonly forwardDiscoveredBatch = async function (
+    this: SynapseHTTPAntispamRoomDiscovery,
+    rawEntries: [StringRoomID][]
+  ): Promise<void> {
+    const entries = rawEntries.flat();
+    const storeResult = await this.hashStore.storeUndiscoveredRooms(entries);
+    if (isError(storeResult)) {
+      log.error(
+        "Unxpected error while trying to store undiscovered rooms",
+        storeResult.error
+      );
+      return;
+    }
+    for (const roomID of entries) {
+      this.discoveredRooms.add(roomID);
+    }
+  }.bind(this);
+
+  private readonly handleCheckEventForSpam = function (
+    this: SynapseHTTPAntispamRoomDiscovery,
+    { event }: CheckEventForSpamRequestBody
+  ): void {
+    if (event.type === "m.room.member") {
+      if (!this.discoveredRooms.has(event.room_id)) {
+        this.batcher.add(event.room_id);
+      }
+    }
+  }.bind(this);
+
+  private readonly handleUserMayInvite = function (
+    this: SynapseHTTPAntispamRoomDiscovery,
+    { room_id }: UserMayInviteRequestBody
+  ): void {
+    if (!this.discoveredRooms.has(room_id)) {
+      this.batcher.add(room_id);
+    }
+  }.bind(this);
+
+  private readonly handleUserMayJoin = function (
+    this: SynapseHTTPAntispamRoomDiscovery,
+    { room }: UserMayJoinRoomRequestBody
+  ): void {
+    if (!this.discoveredRooms.has(room)) {
+      this.batcher.add(room);
+    }
+  }.bind(this);
+
+  unregisterListeners(): void {
+    this.synapseHTTPAntispam.checkEventForSpamHandles.unregisterHandle(
+      this.handleCheckEventForSpam
+    );
+    this.synapseHTTPAntispam.userMayInviteHandles.unregisterHandle(
+      this.handleUserMayInvite
+    );
+    this.synapseHTTPAntispam.userMayJoinRoomHandles.unregisterHandle(
+      this.handleUserMayJoin
+    );
+  }
+}
diff --git a/src/protections/RoomTakedown/RoomTakedownProtection.ts b/src/protections/RoomTakedown/RoomTakedownProtection.ts
index ae6b60c5..6d3ff8a4 100644
--- a/src/protections/RoomTakedown/RoomTakedownProtection.ts
+++ b/src/protections/RoomTakedown/RoomTakedownProtection.ts
@@ -6,6 +6,7 @@ import {
   AbstractProtection,
   ActionResult,
   describeProtection,
+  Logger,
   Ok,
   PolicyListRevision,
   PolicyRuleChange,
@@ -21,12 +22,13 @@ import { Draupnir } from "../../Draupnir";
 import { StandardRoomTakedown } from "./RoomTakedown";
 import { RoomAuditLog } from "./RoomAuditLog";
 import { SynapseAdminRoomTakedownCapability } from "../../capabilities/SynapseAdminRoomTakedown/SynapseAdminRoomTakedown";
+import { ResultError } from "@gnuxie/typescript-result";
+import {
+  RoomDiscovery,
+  SynapseHTTPAntispamRoomDiscovery,
+} from "./RoomDiscovery";
 
-// FIXME: We still haven't figured out how to poll for new rooms via the
-// Synapse admin API.
-
-// FIXME: We need to add the stores to draupnir somehow.
-// probably from the toplevel.
+const log = new Logger("RoomTakedownProtection");
 
 type RoomTakedownProtectionCapabilities = {
   roomTakedownCapability: RoomTakedownCapability;
@@ -48,7 +50,8 @@ export class RoomTakedownProtection
     capabilities: RoomTakedownProtectionCapabilities,
     protectedRoomsSet: ProtectedRoomsSet,
     hashStore: SHA256RoomHashStore,
-    auditLog: RoomAuditLog
+    auditLog: RoomAuditLog,
+    private readonly roomDiscovery: RoomDiscovery | undefined
   ) {
     super(description, capabilities, protectedRoomsSet, {});
     this.roomTakedown = new StandardRoomTakedown(
@@ -69,6 +72,10 @@ export class RoomTakedownProtection
   ): Promise<ActionResult<void>> {
     return this.roomTakedown.handlePolicyChange(revision, changes);
   }
+
+  handleProtectionDisable(): void {
+    this.roomDiscovery?.unregisterListeners();
+  }
 }
 
 describeProtection<RoomTakedownProtectionCapabilities, Draupnir>({
@@ -81,13 +88,35 @@ describeProtection<RoomTakedownProtectionCapabilities, Draupnir>({
     roomTakedownCapability: SynapseAdminRoomTakedownCapability.name,
   },
   factory(description, protectedRoomsSet, draupnir, capabilitySet, _settings) {
+    if (
+      draupnir.stores.hashStore === undefined ||
+      draupnir.stores.roomAuditLog === undefined
+    ) {
+      return ResultError.Result(
+        "This protection requires a hash store and audit log to be available to draupnir, and they are not in your configuration."
+      );
+    }
+    const roomDiscovery = (() => {
+      if (draupnir.synapseHTTPAntispam !== undefined) {
+        return new SynapseHTTPAntispamRoomDiscovery(
+          draupnir.synapseHTTPAntispam,
+          draupnir.stores.hashStore
+        );
+      } else {
+        log.warn(
+          "synapseHTTPAntispam is not configured for this draupnir, and will not be used for room discovery"
+        );
+        return undefined;
+      }
+    })();
     return Ok(
       new RoomTakedownProtection(
         description,
         capabilitySet,
         protectedRoomsSet,
-        draupnir.hashStore,
-        draupnir.auditLog
+        draupnir.stores.hashStore,
+        draupnir.stores.roomAuditLog,
+        roomDiscovery
       )
     );
   },