Bob The World Eater

You can use either ability once per turn
•Croak of Doom (2)(B)(B): Target creature gets
-X/-X until end of turn, where X is the number of Frogs you control.
•Frogify (1)(U): Enchant creature. Enchanted creature loses all abilities and is a blue Frog creature with base power and toughness 1/1
Swampwalk: This creature can’t be blocked as
long as defending player controls a Swamp