Daimond 5 mid laner that just came up with the idea of Presence of Mind also working so you dont lose any energy, zed, shen, akali, kennen but whatever just up vote or down vote if you think its a good idea, because there isnt a single rune that has anything to do with energy so yea would be kinda cool if there were one 
Manaflow band has to do with energy (despite the name), and causes the ability to cost no energy and restores energy.
Whether that one should impact energy as well though, maybe. Energy champs are pretty intentionally gated in how spammy they can be in their abilities (which is why they have energy rather than mana), so there might be undesirable consequences in some situations. Haven't put much thought into it though, so it might be viable.
and yes 5 sec might be to broken so 3.5 or 3 sec might be a good time
