No way to win with Ekko
Nerf his base damages and buff AP ratios, and Full AP Ekko becomes stupidly OP and it encourages him to build one or two AP items for crazy damage. Nerf AP ratios and buff bases, and he goes full tank or ap tank. He has too much utility for an assassin, which predisposes him to going tanky simply because he has a slow, an aoe stun, another slow, a speed boost, an AOE burst even when not full AP, and stupid chase potential.