Whenever Crypt Cobra attacks and isn't blocked, defending player gets a poison counter. (A player with ten or more poison counters loses the game.)

When Serpent Warrior enters the battlefield, you lose 3 life.

Defender (This creature can't attack.)

: Destroy Wall of Vipers and target creature it's blocking. Any player may activate this ability.

: Choose a color. Whenever Zombie Boa becomes blocked by a creature of that color this turn, destroy that creature. Activate this ability only any time you could cast a sorcery.