Arahbo, Roar of the World

Eminence — At the beginning of combat on your turn, if Arahbo, Roar of the World is in the command zone or on the battlefield, another target Cat you control gets +3/+3 until end of turn.
Whenever another Cat you control attacks, you may pay {1}{G}{W}. If you do, it gains trample and gets +X/+X until end of turn, where X is its power.

Aven Mindcensor

Flash
Flying
If an opponent would search a library, that player searches the top four cards of that library instead.

Alms Collector

Flash
If an opponent would draw two or more cards, instead you and that player each draw a card.