1. Trap placement
2. Grenade targeting
3. Buff/Debuff targeting
4. Attack targeting

CTD only occurs(for me, and only on occasion, not always) when an ability is activated but not confirmed.
i.e. Shoot/Build barricade/Homemade grenade, when moving the player to check hit %, repositioning barricade hologram, adjusting grenade arcs to place the damage sphere.

Ive had CTD with grenades beeing thrown but only in coop. Most of the time crashes 1 or both players.