So apparently there is a bug on summoners rift where one can just barely see over the tri-bush cliff (no wards!).
As far as we know it's only blitzkrank that can be seen (we tested a few champions) - perhaps due to his large model/hitbox?
Blitz can even move back and forth a bit (like a range of 100-200 units) and still be seen. And it's definitely real vision - Hecarim can E and dash over the wall onto blitz.
Edit: we didn't test whether this is the case on the upper/blue side tri bush
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