As long as you manage his crystallisation stacks, he pretty much destroyed them by shaving all of their BRV gain. Unless they go into that hard 0 HP damage aura phase, Jergan pretty much bypasses their mechanics without needing to BT. His crystal fists with rainbow numbers also batteries him back to pretty much mBRV, so even under 90/90 reduction he would still be dishing out decent damage with skills (S1/S2) that are not ignore defence moves. He is quite self-sufficient.
Obviously his damage (especially his BT finisher) can be optimized in some ways, but he does not need much to function as intended. How you use his BT is also quite flexible, depending if you want an absolutely bombastic damage phase, strong finisher or maintaining a steady stream of capped BRV and HP damage for a longer period of time. Overall quite a variety of ways and purpose you can use him despite being a selfish DPS (e.g. phase pusher, Brv shaver, friend unit).
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