Affinitybreaker is forged from Nether Eggs. These materials are rewarded when you defeat Agreth, The Nether Spider who appears in Rotations 1 and 2.
This set is probably the worst of all the Doom Tower Artifact sets. The description suggests the effects of converting weak hits is very powerful however when calculating the actual impact, you only reduce the impact of weak hits by 7%. This is because when you attack you have a 35% chance to weak hit if you are weak affinity. The 20% only applies when you weak hit and not on every attack. Instead of weak hit chances becoming 15% you actually calculate this as 35% * 20% = 7% chance Affinitybreaker works. Therefore this reduces the weak hit chance by 7% meaning you still have a 28% chance to weak hit.
Additionally, the 30% critical damage is additive only therefore its weaker than 2 Critical Damage sets (40% total). Arguably for a 4 piece commitment – the rewards from this set are not super desirable.
We don’t recommend you farm this set however sometimes the forge can throw out great pieces.