When you prevent damage to a Ground unit or Character, attach Greef Karga's Optimism to that unit.
Equipped unit gets Damage Control 1.
Equipped Greef Karga also gets Lucky 1 and can't lose Lucky.
Keywords
Damage Control
Damage Control X: A cumulative, triggered ability that means, "When your build step starts, you may remove up to X damage counters from this unit."
Equip
Equip: A selective effect on Equipment activated during the build step that means, "Attach this Equipment to a unit. Play only during your build step." You can pay the Equip cost only once per turn.
Lucky
Lucky X: A cumulative, static ability that means, "Each time this unit attacks or is attacked, you may re-roll up to X of this unit's attack dice or have your opponent re-roll up to X attack dice against this unit." Both players can use Lucky effects according to the rules for POP chances. Lucky is used only once after all triggered re-roll effects resolve. You can't re-roll more dice than are rolled for the attack. You may choose to roll any number of dice up to the Lucky value.