If all targets for the chosen modes become illegal before a spell with spree resolves, the spell won't resolve and none of its effects will happen
Bumbleflower is a 1/5 with vigilance, meaning she can offer plenty in the way of defense, but combat isnt where this rabbits real strength lies
Other cards that help include Evenly Matched, Nibiru / Ra - Sphere Mode, Lava Golem
Giving you a choice between making a 2/2 cat beast token and giving your creatures a +1/+1 counter and vigilance for a turn, upon Landfall, Felidar Retreat is always useful for as long as it sticks around
Perhaps the most powerful Colorless-type card in the game is Noctowl because it searches for two Trainer cards in the deck when it evolves from Hoothoot
(I have so many pins from Crown Zenith triple blisters that I might die.) And, and this is important, its worth stressing just how lovely the bulk is in 151