Please reduce the cost of Singe's Ultimate

Not much else to say, I mean why does an ultimate that grant a paltry amount of mana per 5 have a 150 mana cost? In my opinion by doing everything it feels as if it does nothing. Fling is already an immense mana check, no need for the ult to have one as well. Drop it down to 100 Mana, or hey, remove it all together, why does drinking a POTION cost mana anyway?

(Bonus round: if you ever rework Singed let his ult buy upgraded insanity potions from the shop Gangplank style)