There are several cards that add to the number on an ability or cause it to fire more than once. Stack those together and you can make any card's ability happen many, many times.
Hive and Toucan together can get pretty nuts. I'm in the middle of a game right now, waiting for it to finish summoning hundreds and hundreds of bees, giving me a bunch of gold for each one.
Just a heads up: if you use enough powerups with the Whale to summon Scouts, you can get into a situation where it's summoning hundreds of scouts at a time, making the game run too slowly to continue.