{Ajani, Caller of the Pride}
Does his +1 ability mean I can choose to put no +1/+1 counters on any creature? Since it says "...up to one target creature..." Can I choose zero target creatures?
Yep! From the Gatherer rulings:
7/1/2012 You can activate the first ability without a target. You'll still put one loyalty counter on Ajani when you activate the ability.
RESOLVED