Gravelgill Duo

Persist (When this creature dies, if it had no -1/-1 counters on it, return it to the battlefield under its owner's control with a -1/-1 counter on it.)

Whenever you cast a white spell, this creature gets +1/+1 until end of turn. Whenever you cast a blue spell, this creature gains flying until end of turn.

Counter target blue instant spell.

Blue creatures you control can't be blocked.

Fear (This creature can't be blocked except by artifact creatures and/or black creatures.) 2UB: Each unblocked creature has base power and toughness 4/1 until end of turn.

(2/G can be paid with any two mana or with G. This card's mana value is 6.) Until end of turn, target creature gets +4/+4 and gains trample, wither, and "When this creature attacks, target creature blocks it this turn if able." (It deals damage to creatures in the form of -1/-1 counters.)

Enchant creature As long as enchanted creature is red, it gets +1/+1 and has double strike. (It deals both first-strike and regular combat damage.) As long as enchanted creature is green, it gets +1/+1 and has trample.

Destroy all Auras and Equipment attached to target creature.