Sejuani, the Bear Cavalry

Flash, Trample, First strike, Haste
Whenever Sejuani, the Bear Cavalry comes into play, create a 5/6 green artifact bear creature token with trample and haste named Bristle.
Whenever Sejuani, the Bear Cavalry and Bristle attack or block in the same phase, both gain indestructible, hexproof, and +3/+0 until end of turn.