Yes, thats why I mentioned ini shenanigans.
1) Use skill turn 1
2) Tank for 2 turns
3) Recover at the end of turn 2
If your fat & mdef is sufficient – immortality.
I dont get it… where you get tank for 2 turns?
It would be a 1-round ability, so you spent 4AP and 15Fatigue for the boost. If the brother is fresh, then it will boost your Health (f.e.130Fatigue + 70HP = 200HP). If he gets hit, he really gains Fatigue considerably, he loose his Initiative, he loose his Zone of control
Recover ability 2nd round will remove 1/2 Fatigue back, however you cannot activate Nimble again that round (it cost 4AP) so this round any hit goes directly to HP pool. Going naked to the battle would still be a suicide.
I dont find this model overpowered or immortal as you depict it. It gives you relatively safe round, whenever the brother is fresh.