| Infsol1978 |
In one D&D campaign world I ran, the party came upon an arsenal of "golem armor" of various kinds (Adamantine, Mithril, Iron, Stone, etc), along with a collection of talismans. Each talisman was keyed to one specific golem. The "golem armors" were considered magic items and vehicles, as well as constructs.
If you had the correct talisman for a golem, and spoke the correct command word while touching that golem, you would be magically absorbed into the golem and assume control over it, like a Synthesist Summoner does with their eidolon. The physical body of the 'pilot' was tucked away in a pocket dimension inside the golem, while the pilot took spiritual possession of the golem. There were likely certain conditions and game effects which could force the golem to eject the pilot as well, but we never really explored that aspect of it.
The requirements of the talisman, command word, and physical contact were all security measures to prevent these war machines from being captured and used against their creators, although the talisman itself could be stolen if the owner did not take sufficient precautions. It was never decided what would happen if a talisman were destroyed or damaged. The talisman went into the golem along with the pilot, though, so it would have been pretty hard to disable a piloted golem by targeting the talisman.
The party also Awakened a couple of them, which was pretty cool too. At one point the party gave back the Awakened golems their own talismans so no one could ever possess them against their will.
It would be cool if they did something like Voltron. Where the mechs could merge together into one. Each pilot could carry the "key" that enabled them to pilot the individual mechs.