Merfolk Trickster

If the target creature has an ability that triggers when it becomes tapped, that ability triggers before it loses all abilities.

If the target creature has power and toughness written as */* with an ability that defines its power and toughness, it’s 0/0 when it loses all abilities. If its power and toughness are written as */*+1, it’s 0/1, and so on.

Once you announce that you’re casting a spell or activating an ability, no player may take other actions until the spell or ability has been paid for. Notably, players can’t try to remove a permanent’s activated abilities to stop them from happening. Once activated, the ability on the stack will resolve even if the creature loses the ability.