Actually D&D gives you the tool to correct this: a DM. A point of a DM is to handle silly situations like this (unless everyone wants silly of course).I had a rogue in a five foot wide corridor, no exits, no cover, nothing, and a mage dropped an 8th level spell on him, filling the entire corridor with napalm. No damage. Thanks, D&D.
I have thought about require a reaction to move out of the area of effect to avoid all damage.Just let characters move when they make a successful Dex save. Easy fix.
It's because canonically, fireballs aren't the awesome explosions of hellfire we all imagine, but a sad, dumb little 'whuf' of flame that lasts less than a second.I mean hell we could go one step deeper. Its not just evasion, how does anyone take half damage from a fireball without moving?
You could go another step and ask how a high level fighter can get hit by several fireballs and be running around with less penalties than from a forced march (exhaustion). Each of those fireballs would easily kill an entire crowd of peasants, so clearly it isn't because a fireball isn't deadly.I mean hell we could go one step deeper. Its not just evasion, how does anyone take half damage from a fireball without moving?