Whenever an AOE spell is cast, the actual target center (for circles) or target angle (for cones) differs from the intended target by a factor of 5 feet/degrees * spell level / caster level. Direction of deviation is determined by throwing 1d8 with 1 representing “north or up” and the clockwise each subsequent number representing a quarter change (1d2 for cones left or right)
My players and I use Fantasy Grounds for our online role playing.
Up until now, whenever there’s an area of effect spell (spike growth, fireball, etc) I simply draw a circle or whatever center at the point they indicate and we use that to track the AOE of the spell. That’s all fine but due to the mechanics, it produces a couple of undesirable consequences:
- They get laser like precision, being able to cast spells that affect the maximum number of enemies and never hit an ally.
- They are aware of where effects start so they can avoid the affected areas while enemies don’t.
For the second point we’ve agreed to simply not show them where the exact area of effect is, I will see it but they won’t. That improves it but they can arguably still keep it in mind with precision by simply counting squares on the map.
We have, therefore, agreed to introduce some randomness in the “aiming” of the spell. You intent to put the center somewhere but, since you’re just human after all, you don’t get it perfect.
Current line of thought is to make it small but noticeable, maybe up to 2.5 to 5 feet away from your intended target. That’s easy to make it random but there have been chats for making it rely on spell caster level vs target ability or vs spell level (I.e. distance from intended target is 5 feet * spell level / caster level).
You are a level 5 wizard casting a fireball spell. You select a target center, and roll 1d8 getting 5. The fireball impacts at a point roughly 3 feet below your intended location.
After seeing the linked question, I still prefer this to a check against an AC. Isn’t this system no matter how good you are you’ll never get it exactly right (which is how good aim works in real life). The better you are, the closer you get, but a level 15 wizard will still get it wrong by a feet.