"Since your last turn" means between the end of your last turn and now. Your last turn does not qualify, your current turn does.
100486
Daemonic Possession
Choose a minion that was controlled by another Methuselah who has been burned since your last turn. Move the chosen minion from their owner's ash heap to your ready region with 1 blood or life, and lock them.
As above, but do not lock the chosen minion.
Rulings
Cards requiring a discipline come in play at the inferior version.
Requirements do not apply. If the cost is X (e.g. Reanimated Corpse), X is zero. If the effect puts/moves a minion into the ready region, that minion can act this turn.
Is an undirected action, even when targeting another Methuselah's ash heap.
Cannot be played if no target is available in any Methuselah's ash heap.