This card was made for Drax. I'm surprised it was not put into his pack originally. Drax is going to take damage even with Parry, Subdue, and Deflection at some point. Getting a tough for one cost and a hit seems reasonable.
Hero Response: After a guardian character takes any amount of damage from an attack, give that character a tough status card.
This card would also go really well with the Groot Ally. With 6 health he has a really good chance of surviving an attack. He will then heal 2 health and with the Tough he will heal 2 more health the next time he is attacked.
Obviously great with Drax who needs to get hit a lot. But it also works very well with Star-Lord since his allies always have the GUARDIAN trait, making them very efficient blockers. And it can be a great combo with the Groot basic ally, since he can block an attack from a minion, get tough, heal and in the next turn block an attack from the villian and heal once more.