Can we make a change to this mechanic? No need to remove it completely, but how about making a buff stack mechanic that returns the HP (or some of it) after some time? 

-every time axian eats Nova's hp, the character is given 1 stack of a buff that does nothing on it's own

-this buff will last 10-30s(depending on how you want to balance), refreshing the timer every time axian is summoned again

-when the timer runs out, Nova is healed by an amount depending on the size of the stack

"Well hold on what about PVP -nova getting healed in the middle of a combo, wouldn't this be way to big of a buff?", hitting nova while she's blocking already triggers an Axian summon, this would refresh the stack timer. Devs could also make the stack have a longer timer, or limit the max amount of stacks you can build up, or lower the amount of health returned per stack, or a mix of all these. Don't forget that the damage nova is healing is something that was done to herself and not an actual opponent.