{R}{R}, {T}: Target creature you control can't be blocked this turn. Destroy it and Goblin Sappers at end of combat.
{R}{R}{R}{R}, {T}: Target creature you control can't be blocked this turn. Destroy it at end of combat.
If you activate the ability during the end of combat step, the creature will be destroyed at the beginning of the next end of combat step, even if that step occurs during a different turn.