I'm thinking specifically about the D&D 5th edition Moonbeam spell. Given that we don't play with a grid, and players are free to place the centre of the beam anywhere they like, there is a desire to place it such that an enemy is in the beam, while player characters they are in combat with are not in the beam.
There are two specific situations I want to consider and how they might play out.
Firstly, assuming the combatants aren't using ranged weapons, or weapons with unusual reach, does attacking the AOE-engulfed target with a melee weapon result in the attacker's hands potentially entering the AOE and thus incurring damage?
Secondly, given that combat is not really static, with each combatant making a single swing in their allotted 6 second turn, is it more realistic (for want of a better word) to assume that two combatants next to each other, engaged in dynamic melee combat are inseparable for constant-effect AOE spells? (I can imagine a situation where an instant-effect like fireball can be arranged not to hit your friends, so I'm concentrating here on constant-effect spells like Moonbeam).
So the question is, can constant-effect spells like Moonbeam be placed in such a way that two combatants, in melee combat with each other, can be on either side of the AOE, one affected and one not for the entire duration?
