2017-02-09 : Each creature you control has Rishkar's mana ability as long as that creature has any kind of counter on it. The effect isn't limited to those with +1/+1 counters.

2017-02-09 : Rishkar can be a target of its own triggered ability.

2017-02-09 : You can't target the same creature twice to have one recipient get two +1/+1 counters.