Interplanar Brushwagg (CMB1-079) - Mystery Booster Playtest Cards 2019

Interplanar (This creature enters onto the interplanar battlefield. Players can't control creatures on the interplanar battlefield.)
Vigilance, haste
Whenever a player attacks with a creature with power 4 or greater, Interplanar Brushwagg also attacks the player or planeswalker that creature is attacking.