If you could redesign Havoc T21 with the caveat Eye Beam had to be the focus, what would you do?
What if...
2p = Increases Eye Beam damage by X% (because 2p has gotta be boring).
4p = You can move, and continue to cast other spells and abilities during Eye Beam, Eye Beam is also removed from the GCD.
or maybe
2p = Each time Eye Beam deals damage to a target, that target takes 1% extra damage from the DH for 8 seconds.
4p = When Eye Beam expires, remove all fury costs for Chaos Strike for 8 seconds. Fury generated while this is active is pooled beyond the normal cap (to a maximum of 2 times the normal cap).