Resisting AoE, why can one protect all?

[PiXeL01]

One of the few things I disagree with when using the ED4 ruleset is the rule that AoE spells are compared against the highest defense rating only, instead of against each target individually.

I was wondering why this decision was made.

Personally I have been thinking to change it via a house rule, but I was wondering if that would be too deadly for my players.

[Mataxes]

It's related to how other multiple target effects work. For example, a group-affecting talent targets the highest defense in the target group (sometimes with +1s, sometimes not).

It's also not new to ED4, this has been an aspect of (at least some) AoE casting since ED1.

I'm at my day gig, so I can't go into more detail right now.

[Telarus]

In my view, it comes back to the metaphysics of spellcasting. As the caster weaves threads they build an additional mana charge into a matrix. The Spellcasting roll happens before the spell physically manifests, and it determines whether or not an "astral arc" has been successfully drawn to the target. If the Spellcasting roll failed, all that gathered mana has been flung randomly all over the local astral plane and lost (maybe some of it bleeds into the physical plane), instead of "grounded" into the target pattern(s) to manifest the spell effect.

The effect on AoE spells is that sometimes you can't "get a lock" on a group of targets if one of them has a high MD. Best bet there is to try to disperse the targets or take "slices" out of the group. Note that this does stand in contrast to what traditionally happens when fantasy wizards with fireballs (local artillery) shows up, as most other games have the tight formations of mundane troops spread out so they don't all get toasted at once. Casters and other high Per characters can change that up a bit.

[PiXeL01]

Thank you both. It makes sense when explained like that.