The item is pretty good, I do think it being a T2 may be a bit much though. Being able to copy 80% of a target's healing is very strong espeially against some beefy ones like Geist or Victor. Personally I would put this in T3, change the replicated healing to maybe 50%? and maybe change the stats it gives to extra fire rate instead of weapon damage.
My reasoning for having fire rate instead of weapon damage is that it would allow for counters like Suppressor to work, making this item not feel uncounterable if fought against.
Since your description doesn't provide any cooldowns or durations I would say have maybe around a 3s debuff duration on a 1s cooldown, with the extra fire rate making more sense for this item as it would allow a more effective application of the item's effect.
I do like the idea of stealing or copying a target's healing, it adds a different way to deal with overhealing targets instead of just using anti-heal items. Though you have to sort of keep in mind that heal replication will contend with healbane and will have to be balanced accordingly as to not outweight antiheal alltogether.
I think it would be cool to have anti-heal be more of an AoE or group based debuff while heal replication be more of a duel based debuff, in this case it would make sense if the item's effect applied to only a single target and would switch to the target with the highest source of healing.
- Anti-heal could be more of a group based debuff, being more effective during team fights and providing a good source of sustain shred. You can sort of compare this to Pocket's ult where it's like a clock ticking down, the more you stay in a fight with the debuff on the worse it gets for you without any way to heal or survive, forcing the affected team to try and retreat.
- Heal Replication would be more of a duel-based or 1-on-1 based debuff, mostly applying to single targets and allowing players to more easily match up to tanks when alone. Would not be as good as anti-heal during team fights as the debuff would only benefit single people. (Unless everyone gets Draining Shot planning to target one or two big healers during a fight which would imo be a cool way of shutting down someone from a fight.)
