Atrox, Primeval Apex

Trample, Vigilance
When Atrox, Primeval Apex or another creature enters the battlefield under your control put 2 +1/+1 counters on Atrox, Primeval Apex.
Beasts you control get +X/+0 and Vigilance, where X is half the number of
+1/+1 counters on Atrox, Primeval Apex.