Devilmite Beam is an all-or-nothing Ultimate Blast, which uses the opponent's "evilness" as a multiplier for the attack.
Against 100% evil characters, it deals 27270 (unboosted) and 30000 (boosted), which is its highest amount of damage.
Obviously, the Ultimate Blast will not work against pure-hearted opponents, but the lowest amount of damage however is 1370 (unboosted) and 1500 (boosted).
For ease of access, here is a tierlist showcasing the evilness of every character in the game.
