Magic Points
MP or Magic Points are a stat in many games in the Dragon Quest series. These are measures of how many spells a character can cast. Every time a character casts a spell, an MP cost is deducted from their Maximum MP value. When a character runs out of MP, they will not be able to cast any more spells, and will have to resort to their weapon or some other form of attack. (If a character attempts to cast a spell whose MP cost they cannot pay, it fails.) Therefore, characters who are heavily dependent on spells are at a distinct advantage without any MP, and so have a lot of it; characters structured around attacking physically tend to have few MP or even none at all. A few items can restore MP, and resting at an inn will fully restore it.
Various items and equipment can alter how MP is consumed; for example, one item has a chance of absorbing some of the caster's MP when they successfully cast a spell on the wearer.