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\"I'm happy 'cause I'm practically indestructible! U mad?"\
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Secret of Mana had some balance issues no question, but that was mostly to do with magic stunning the enemy for a long time and making you invincible while casting. Then there's
these jerks who multiply whenever there's fewer than the enemy limit of 3 on the screen. You get no XP or gold when that happens, and the two new ones get full HP meaning you wasted all your time damaging them before (they have strong defence against both magic and physical).
It's against my nature to run from enemies in a game with RPG elements, but your one advantage here is that they move slower than you can run. However, the blue and red ones can freeze (can't move or act) and engulf (can't move or act plus you take gradual damage) you, forcing you to stop and fight while the afflicted party member can't move. Lastly, the gray ones don't do that- instead they simply multiply in a way that one of the copies transforms into an enemy from two whole dungeons ahead of where you are now... a dungeon that itself is considered a massive difficulty spike in the game.
Killing one of these things is always more effort than it's worth, and a waste of precious magic.
More recently I got Devil Survivor: Overclocked for Christmas and while I'm sure there's worse things waiting for me ahead in the final day, Decarabias need to stop appearing before I break something or someone. The flying starfish have resistances to everything except Lightning, cast a strong all-party barrier spell that blocks everything, even Almighty attacks, and guarantees that you have to give your enemy extra turns by attacking them and being blocked, and they're always the leader of their teams meaning killing them first denies you XP and Macca in a game where Macca is extremely important and you need all you can get.
They will never kill you (well they do use Agidyne but no biggie), but their buddies will since you can't freaking damage them through all the barriers and they also cast an all-party Mute spell whenever they're not using their barrier, meaning you can't use Lightning. Worse, if one of your demons does die, the Decarabia heals the entire enemy team back to full, both HP and MP, again undoing all your hard work. A party of three Decarabias won't kill you- they'll just make the battle last about ten rounds longer than it needs to.
Oh, and they show up in a mission with a time limit of six rounds to kill everything.