this is a good idea but needs alot of work
what about this? - if not we all can keep changing stuff and make a forum collab champion :P
Reserves (Drink blood)
Each time Q and W abilities are used, the champion gains 1 reserve stack for 5 stacks.
Active (any amount of stacks)
Increases movement speed and restores X amount of HP per stack
AoE buff after drinking the reserves, the more stacks the bigger the impact
The sight of blood dripping down from the mouth of the champion scares nearby enemy champions, reducing there defences by X amount
if used at 5 stacks, the champion becomes immune too all damage for X amount of seconds
This with her passive and possible Life Drain (below) would make the champion deadly
Life Drain (Like Fiddlesticks ability) - (Convert minion) - Channel spell, if hit channel is broken (Enemy champion can still be hit however by teammates)
The champion sucks the blood of a nearby enemy champion for x amount of damage for 3seconds, both champions are stunned for the duration and cannot move or attack - if the channel is broken you become dazed and move 75% slowly for 3 seconds - if the channel was successful the enemy champion slowly bleeds for 5seconds.
(the higher the level of the spell the lower the dazed effect - 3, 2.5, 2, 1.5, 1 second)
i like the bat swarm idea, it has too be a fear effect.
Maybe instead of the champion turning into bats
The Champion sends a swarm of bats too the target location, any champion the swarm hits on the way will cause them to be feared, the champion will only stay feared if caught within the swarms target location for X amount of seconds.
i would actually like the idea of a vampire champion.