Groot is in hero form and has 2 growth counters and a tough status card. If he takes 2 damage, I'm thinking I have to remove 2 growth counters first, as it is a forced interrupt, before I would get to discard the tough status card. Likewise, if I took 3 damage, I would discard 2 growth counters first and then the tough status card for the remaining 1 damage. Rules gurus, take it away! Thanks!
Guardian.
Flora Colossus — Forced Interrupt: When Groot would take any amount of damage, remove that many growth counters from him. For each growth counter removed this way, prevent 1 of that damage.
Outlaw.
Growth Spurt — Action: Place 2 growth counters on Groot (to a maximum of 10). (Limit once per round.)
Groot is an interesting puzzle. Half of his kit wants to stack counters and the other half wants to spend them resulting in a bit of a dilemma. After some testing I think burning through the counters is the answer. You can spend several turns stacking for a big event just to have everything ruined by one bad encounter card.
The ideal scenario would be blocking for a partner, getting hit directly, and ultimately ending up around 2 HP (5 or less if you have endurance). This gives you an excuse to stay down for a couple turns to stack counters. When you flip up you’ll have 1 turn to play your events with your freshly stacked counters before repeating the process of spending them. Obviously this strategy really only works in 2-4 player and really needs to be paired with Justice to help enable your semi-frequent flipping.