SCP-939

Vigilance
If an opponent controls a Human creature,
SCP-939 gains First Strike.
Whenever SCP-939 enters the battlefield under
your control, put a +1/+1 counter on each other
SCP-939 you control.
"SCP-939 are endothermic, pack-based predators
which display atrophy of various systems similar to troglobitic organisms."