User blog comment:Shaw Fujikawa/Custom Champion Revisit - Arvice, the Wandering Psychic/@comment-5638912-20121123021558/@comment-5638912-20121124201055

I know how you want this concept to be, but this isn't World of Warcraft where mages' abilities cost percentages of their mana pools.

I would totally suggest to make them have flat mana costs (progressing per rank). And make them highly cost worthy. Also, find another way to regenerate mana, for example: There's lots of creative ways to regenerate mana, just find the right one and make the costs flat. For example:
 * Convert 15% of his AP into Mana Regen (or whatever amount you want).
 * Restore an amount of mana upon each unit killed (like or ).
 * Make it regen 1% of his maximum mana after 6 seconds of being out of combat (or not hit by an enemy champion).
 * Refund a percent of the mana cost whenever an ability hits an enemy (but this only would be ok if he had more than 1 skillshot, which he doesn't).
 * Give his ult a toggled off passive, which converts 1% or 2% of his maximum mana as mana regen (or even 3% of his current mana, this would be more dynamic).
 * Q 70/105/140/175/210
 * W 80/130/180/230/280
 * E 100/140/180/220/260