This isn't just a QQ Lee Sin OP thread, I'm just seriously confused why an ult that powerful costs zero energy. I mean, I understand that energy isn't much of a restriction on abilities, (Zed, Akali, etc.) but even so, I can think of very few ultimates that are as impactful in a team fight that that cost the champion absolutely nothing.
The basic answer is that energy champions work best when energy gates the usage of their basic abilities but their ultimates are only cooldown based. In the past, Kennen's ultimate used to have an energy cost, and there was testing done on putting an energy cost on Akali's ult (it didn't ever go to live or PBE). In both cases, it was found to be an unreasonable problem for the champion.
Taking Kennen as an example (his ult is majorly impactful in a teamfight). The main effect of this was that it A. majorly impacted his ability to use their basic abilities in any fight where he would need their ultimate and B. removed his ability to use their ultimate reactively if he used other skills first. The basic tradeoff was that you could either use your basic abilities and not have the ultimate available, or use the ultimate and be unable to use any basic abilities for an extended part of the fight. It was just way to gating. Energy is meant to be a limitation on your ability to fight for extended periods and a requirement that you use the energy recovery mechanics, not just a complete inability to use your full kit in a fight.
Think about other teamfight changing ults, like Sejuani's, Amumu's, MF's, etc. Unless they have burned a lot of mana prior to a teamfight, they can use all their abilities and not worry about being unable to cast their ultimates when they need to, or about being dead in the water after they ult. If Lee's ult or Kennen's ult or Shen's ult had a cost, they would be majorly limited by that. It's just not great design for energy champions.
No energy champions have costs on their ultimates..except maybe shen.
If they added Energy costs on the ults the basic abilities would have to have there energy costs reduced, so that they could actually cast an entire combo. This would make there already mindless spamming of basic abilities even more broken, SO not thank you, ill take no cost on the ults.
