Heimerdinger's Ultimate should not share Cooldowns with his basic abilities
Reference: Rengar (Ferocity). When Rengar's Ferocity is full he can use the upgrade of his ability, even if the basic ability is on Cooldown. Now: Heimerdinger. He CAN'T use his ULTIMATE (upgrade of his ability) if the basic ability is on cooldown.
Result: You basically must not poke before teamfights as Heimerdinger - because you run into danger of not being able to use your ultimate.
PLEASE, make Heimerdinger's ultimate have independant cooldown...