For every ability there is a graphical description explaining from what positions it can be used and what positions it can target.
Those descriptions seem to assume 4 heroes/monsters.
Given that there are only 1, 2 or 3 heroes/monsters, what positions are they on?
Can I target a lone monster (no corpses) with a skill that only hits position 4?
If there are only two monsters and I have a skill which hits both position 2 and 3, do they both get hit?