Tree Grab seems to not use cleave, but some custom area damage similar to cleave.

The differences are:
1. Area. Cleave is trapezoid shaped, while Tree Grab is shaped like a norman window (a rectangle with a semi-circle on one end).
2. Cleave damage is reduced by armor type, but not by armor value. Tree Grab is reduced by both.
3. Cleave does not work with spell lifesteal and spell damage amp. Tree Grab does.
4. Cleave works with proc-based attack damage bonuses (Javelin&upgrades). Tree Grab does not.

I can see the area thing being intended (it basically covers the area the tree visually reaches). But the others seem unintended.

1. If you want the cleave damage to stay relevant in the late game, it should ignore armor value, just like how cleave does.
2. The aoe damage is an attack-based effect. Within the last year, every attack-based effect was made to not work with spell lifesteal and spell dmg amp (cleave, luna glaives, psi blades, splash, all were changed). Tree Grab working with these 2 mechanics goes against that.
3. Every aoe damage that is attack-based considers "conditional" bonuses like bash and pierce (or from abilities like backstab and fury swipes). Tree Grab is the only one that doesn't.