Papyrus

Defender
If Sans is also on the field, add two +1/+1 counters on both. Papyrus is no longer a defender.
Summon a 5/1 gaster blaster whenever Papyrus blocks a creature.
{4}{t}Final strike: As a last resort, destroy all creatures on attacking opponents field.
Hurt me. Break me. As long as I stay determined, you will never harm my friends.