So recently I remembered there were these magnus shields, for both earth and fire and thought it'd be cool to make some strat using them. But couldn't figure one out until I thought about using the earth version against Prime Conduit.
I kept resetting the fight until he was attacking with earth damage, which meant I could use the eternal champion armour and use the caster lean from it, to increase the damage of the skill from the shield. Since the boss has a hit count of 5 on his normal attack, and I toggled the shield to give me 2 charges per hit (You still get charges even if Conduit misses), it means I basically have enough charges to use the skill every turn.
Underwyrmling pet is important because it prevents the boss from using its SP attack that allows him to switch his attacking element.
Music used:
Jyongri - Possession