Currently at Master rank this spell grants. 92 STA 36% Slow Reduction 2221 Spell Mitigation (Ele/Nox/Arc) This equates out to 920-1196 hit points, my suggestion is that it just be 1% per rank of Max HP. At Master rank this is 5% HP. As it is without our Mythical Cloak, Guardians do not have any % HP buffs, something all other tanks have. Hm, on second thought. I guess the fact that ours is the only one with % slow reduction that kinda balances it out. Nevermind, garbage suggestion.
I think iron will is fine. And zerks dont have a % health buff either other than the one from the heroic tree that all share. Or any heath buffs.
That is why I edited the post saying "garbage suggestion, disregard" was a snap-idea I had and posted before I thought about it.