Omen Hawker's mana cannot be used to unlock Rooms
Unlocking the second room in a Room enchantment is an activated ability. But when I tap Omen Hawker to use it's mana to pay for the ability, the game is refusing to use the mana to pay the cost.
-
Rezzahan#77802 commented
Unlocking a room is NOT an activated ability. It is a special action, like turning a face down permanent face up.
709.5e A player who controls a permanent that has one or more locked halves may pay the mana
cost of a locked half of that permanent to give that permanent the appropriate unlocked
designation. This cost is referred to as an “unlock cost.” THIS IS A SPECIAL ACTION (see rule 116).
A player can take this action any time they have priority and the stack is empty during a main
phase of their turn.