Spellbreaker Behemoth

This spell can't be countered.
Creature spells you control with power 5 or greater can't be countered.

Drumhunter

At the beginning of your end step, if you control a creature with power 5 or greater, you may draw a card.
{T}: Add {C}.

Xenagos, God of Revels

Indestructible
As long as your devotion to red and green is less than seven, Xenagos isn't a creature.
At the beginning of combat on your turn, another target creature you control gains haste and gets +X/+X until end of turn, where X is that creature's power.

Forest

Gwenna, Eyes of Gaea

{T}: Add two mana in any combination of colors. Spend this mana only to cast creature spells or activate abilities of a creature or creature card.
Whenever you cast a creature spell with power 5 or greater, put a +1/+1 counter on Gwenna, Eyes of Gaea and untap it.