What kind of trolling exactly is ban worthy?

Example - rat is in our joust match with me and my friend and were winning early on super hard even tho rat continues to dive on 20% health and go 1v3. First time it happens at lvl 4 its like okay fine were ahead and picked up 2 kills. But throughout the game he missed waves, taunted and spammed his laugh while getting outfarmed and underleveled by a large margin.

In all reality he threw the game, because he purposefully did such things. Howrver reporting him and leaving a message explaining im wondering is that really enough? This happens a lot in games when ppl get salty. I csnt really put it as "feeding" because he was 3/5 while i went 5/5 but him not helping, missing waves on purpose, letting them take our phoenix without defending etc are all actions that deserve a penalty.

Does hi rez watch gameplay to determine? Sorry if its been asked before im just curious, because its not blatant trolling or inactiveness that will normally warrant a ban but imo its just as bad if not worse.