QGJ zeta lead adds up to 1200 offence, so adding 5000-9000 offence to barris is not a good plan
mod sets even only give up to 2000-3000 and thats 6dots
with all the massive amounts of damage in the game, whatever makes them fall below 50% hp probably kills them, making the stealth almost never proc, you could raise the health % to 65% or something if youre set on stealth, but a big part of multiplayer teamfights (in real time games) is the healthiest person body blocking (physically moving themselves in between the enemy and their team, aka "taunting". and while yes, the almost dead people run away, they cant run faster than anyone else so its only via the enemy being slowed that distance and safety are made.
i suggest something like
"Healer allies gain +30% Max Health and gain Offence equal to 5% of their Max Health. Other allies receive half the Health and Offence bonuses. Whenever a Healer ally is Critically Hit, they gain Speed Up for 1 turn. Whenever a Healer ally falls below 65% Health, they heal themselves for 10% of their Max Health and gain Stealth and Evasion Up for 1 turn."
this gives them much more (reasonable with only 5%) use of the leader ability while still being able to deal damage with +2500-4500 offence (which is highest from any leader i can think of)