Rewind

Whenever Karn blocks or becomes blocked, it gets -4/+4 until end of turn. 1: Target noncreature artifact becomes an artifact creature with power and toughness each equal to its mana value until end of turn.

(T: Add G.)

Flying When you cast a creature spell, sacrifice this creature.

(T: Add B.)

(T: Add U.)

(T: Add R.)

Echo G (At the beginning of your upkeep, if this came under your control since the beginning of your last upkeep, sacrifice it unless you pay its echo cost.)

(T: Add W.)