Atarka, The Primal Inferno

Flying, Trample, Haste

When Atarka, The Primal Inferno enters, it deals damage divided as you choose among up to three target creatures equal to the number of +1/+1 counters on creatures you control.
Whenever a Dragon you control attacks, put two +1/+1 counters on it.

Join Forces( You can have two commanders if both have join forces.)