The absorb damage sounds good, it works fine with the numbers, just don't know how to spread absorb effect to all allies, because I'm using status effect with absorb 50% damage. :)
So I've finally createad a passive ability with that absorb status effect. Tried to use "Add Temporary Ability" in Battle events to all allies, but they don't profit from it...I think that it's because I'm using Calculate node, that works between User and Target, so I have to find other solution...
When I replace Calculate node with "Use Ability Calculation" then I can define 'All Allies' as users, but then they all do also damage to the target...
Edit: Looks like I've managed to solve it with 'Change Status Value' node, which has my lifesteal formula in it. Still would like to know the how to get it work with the absorb effect too... :)