
When this creature enters, choose one —
• Put a +1/+1 counter on this creature.
• Destroy target artifact.
"I have no clan, but I still have purpose."
Illustrated by Craig J Spearing
Released on January 23, 2015
You choose which mode you're using as you put the ability on the stack, after the creature has entered the battlefield. Once you've chosen a mode, you can't change that mode even if the creature leaves the battlefield in response to that ability.
If a mode requires a target and there are no legal targets available, that mode can't be chosen. You must choose another mode if able.