I was thinking that if you wanted to balance tank Ekko you could simply make his cooldowns scale with ap. By doing so it hurts tank Ekko's mobility and damage output while also buffing assassin Ekko depending on what ratio Riot thinks up.
Balance options:
**2) Rework/delete. **
To reduce the damage, just lower the "free" per level scaling damage and convert it into AP scaling. Like, instead of gaining 25 damage per level, gain 20 per level and give him a ratio .1 higher. You can do the same for the ult, just lower the healing to 15% and increase AP scaling.
