It is a skill and magic point based system - there is a single skill that covers spellcasting, modified by Int.
You start the game already knowing most of your spells, even the ones that you cannot yet cast. (This is actually one of the parts of the magic system that I don't like. Actually, it is pretty much the only major part of the magic system that I do not like.)
Spell points are regenerated per scene, not per day - so when you have finished with one part of an adventure, then go off to the next, you get all your spellpoints back. This is actually the part that I like best about the system. It can end up very cinematic in regards to Mages blowing through their spells.
The spellpoint cost is one per level of the spell, plus any tricks that you might add to the spell. So 0 level spells are free - you need to roll for casting, but you can do it all day long. This is kind of important, because a starting Mage can only cast 0 level spells.
And with spells that actually do cost points, if you get a crit then you get your spell points back. But an awful lot of casting, even for moderately experienced Mages, is going to be 0 level spells.
The Auld Grump