The Witch King

Fated Fortune passive gives us 12%critical damage for 7 seconds per crux generated and consumed. Eat Doritos fast enough to whale on microtransactions and we can have theoretically 72% critical damage for 7 seconds. 

The Magical combo is Inspired Scholarship<Escalating Runeblades<Escalating Runeblades<Pragmatic Fatecarver as our deadly damage and spender. Fatecarver is more consistent with a built-in shield and anti-interrupt immunity, otherwise a wasted channel ability if we are interrupted. The other spender is Impervious Runeward, a survival flex combo with Audacious Runemend. Runemend also generates a crux that makes up for the spender shield and provides minor heroism below 50% health. Had to drop other abilities and morphs because they spend too much crux and cause awkward rotations that take away the deadly damage output from Fatecarver. 

Pre-buffs and rotation start as, Back Bar: Blockage<Fulminating Rune<Inspired Scholarship<light attack to start the 8-second Whorl of the Depths timer< Front Bar<Deadly Clock<Barbed Trap (purely for the bleed damage as minor force is redundant)<Runeblades twice< Pragmatic Fatecarver. If executed perfectly, Whorl of Depths will go off at the same time the Fatecarver has been cast for a lot of damage.