Blood-thirsty Warg
The Wastes of Eriador#19 (x2/x1)
Enemy
(35) 2 4 2 5

While Blood-thirsty Warg is in the staging area, it gains:

Forced: When it becomes Night, Blood-thirsty Warg engages the first player and makes an immediate attack.

The wold snarled and sprang towards them with a great leap.
–The Fellowship of the Ring