OP Xerath mana trick
Can't believe I hadn't heard about this before.
If you have Manaflow Band or Presence of Mind ready you can start charging Q for free. So then what you do is just don't fire it. It refunds half of its mana cost when you don't fire it. Refunds stack so you profit a ton of mana.
Well, it'll be gone when they update those runes. But right now it's pretty OP.
Downvote me Xerath mains. I've exposed your freelo technique.