1) Pugna ult (usual or aghanim) after 7.10 update: 0 damage (on enemy), 0 hp/mp regen (on enemy or ally).

2) Nyx 3 skill: some enemies after this skill get 0 hp and become invinsible.

3) Phantom lancer illusions after 7.10 update cause SERVER to crash. Just need a lot of them (2 lvl ult + butterly + moonshard).

4) OD Astral imprisonment used on an AM clone cause this clone to stay alive even after the clone time is over. This can sometimes lead to next wave not to start. Maybe (not sure) shadow demon Disruption have the same effect.

5) Blade mail cause a SERVER to crash on Elder titan stone form and Lich frost armor. Both skills have blade mail mechanics. And it seems that blade mail damage with this skills cause an infinite loop.