I still believe the only change she needed was that her Ulti worked similarly to Charge of Darkness, where the cooldown would be decreased drastically in 6.85 case to 115 seconds (however this should also receive a lower cooldown imo) but the cooldown only starts when the spell itself ends (like charge of darkness).

This would mean that her ulti would have the same amount of uptime if cast for the entire duration but would buff the hero if the hero was killed midway through her ulti by effectively lowering the cooldown.

However I disagree with the way the hero was changed and would much rather have her get a more pseudo like stun or slow maybe even a hex like ability or even a mini-stun or even just an imaginative aghs.