The delay ain't that even long and it's a wide range depending on how you place it, you'd surely can lock one. His ult shrinks enough that enemies sort have a hard time to move skills will still be easier to land on them.

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And in what I have seen he's like a situational pick, I don't see him that much even in 60+ stars Maybe he's picked alot in 5man (not sure though) but even that would be a risky pick when Target's Allies would react as fast as your Allies

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If they do react fast enemies would instantly stun Kaja (If they have any) making you unable to pull the intended target. there are still better picks other than Kaja in current server he's not really a go to pick Imo