The most common are enter the battlefield abilities , however some subtypes of battles, such as Sieges, also have triggered abilities when their final defense counter is removed
Homo Ludens ke Karlung, 1965 In between redskins and cowboys there is Homo ludens, the playing man
Then you hopefully draw into your payoff, such as [[Grapeshot]]
Creature Illusion You may have Spark Double enter the battlefield as a copy of a creature or planeswalker you control, except it enters with an additional +1/+1 counter on it if it's a creature, it enters with an additional loyalty counter on it if it's a planeswalker, and it isn't legendary
If you remove Imprisoned in the Moon from a planeswalker after tapping it for mana, you can still activate a loyalty ability of that planeswalker even though its tapped
Sadly, things arent looking good so far, as White Mages Staff and Black Mages Rod both seem somewhat meh