Pushback ability would be interesting. Only the card in the frontline could use this ability. The creature would have a 25% chance to move the enemies front tank 1 space behind, so the second creature in line would be now the front card.
This ability would be a double edged sword:

• in case there is a glass cannon in the second space or a card with reach, then those could be eliminated easier
• in cases, there is a heavy tank in the second line as well, then the healthy tank would come forth and start the fight, giving a better chance for the enemy team to win.

The card with the Pushback ability can only be a high mana tank or a pacifistic card with no attack.
@arkasz

!PIZZA