Yes, but not by adding up. Healing reduction from different sources stacks multiplicatively: two 35% cuts make about 58%, not 70%. Two copies of the same effect don't stack at all, so two teammates with Healbane cut healing no more than one.
How the maths works
Each cut applies to the healing the previous one left. With Healbane (35%) and Toxic Bullets (35%) on the same target, the first leaves 65% of the healing, and the second takes 35% of that, leaving about 42%. That's a 58% cut in total.
So a second anti-heal item helps, just less than its number suggests.
Every anti-heal item
| Item | Cuts healing by | For | How it's applied |
|---|---|---|---|
| Healbane | 35% | 8 s | your spirit damage |
| Toxic Bullets | 35% | 4 s | bullets build up a bleed |
| Decay | 50% | 12 s | active, cast on a target |
| Inhibitor | 40% | 5 s | bullets (also lowers their damage) |
| Crippling Headshot | 35% | 12 s | headshots |
| Spirit Burn | 70% | 8 s | after a burst of spirit damage |
Some heroes bring their own anti-heal through ability upgrades, including Infernus (Napalm), Venator (Consecrating Grenade), Vyper (Lethal Venom), Vindicta (Crow Familiar) and Drifter (Stalker's Mark).
Do slows stack?
The same way: movement slows stack multiplicatively. A 16% slow from Slowing Hex and a 24% slow from Mystic Slow together slow by about 36%, not 40%. Slow resist works the other way: slow resist from different sources adds up, then reduces the combined slow.
Anti-heal also cuts lifesteal. More on that in lifesteal and healing.
Quick answers
Does anti-heal stack in Deadlock?
Different anti-heal effects stack multiplicatively, so two 35% cuts give about 58%. Two copies of the same effect don't stack.
Do two Healbanes stack?
No. Only one Healbane effect applies to a target, however many players have it.
What is the strongest anti-heal item?
Spirit Burn cuts healing by 70% for 8 seconds. Decay is the strongest active, at 50% for 12 seconds.
Do slows stack in Deadlock?
Yes, multiplicatively: a 16% and a 24% slow together make about 36%. Slow resist from different items adds up.