Possession Gates are shards of the Netherworld used by the Overlord to possess minions. In order to activate a Possession Gate the Overlord must send minions at it to run around the shard and one on top of the shard. The first minion sent takes up the place at the top of the gate, and is the one the Overlord ends up controlling, this may be critical. Once the right amount of minions is set, use the Target spell to begin. Once the possession ritual is completed all minions will follow the minion that the Overlord controls.
To end the possession, the possessed minion leader, will have to walk into the Possession Gate field. Should the leader die, this also ends the possession.