You can only used one spell per turn. They're ranged attacks and you can only used one ranged attack per turn.
Page 11 of the 1st ed mini rulebook:
If a unit has
two or more types of ranged attacks (including
magical ones), it can only use one per turn.
For v2, from the shooting phase page, third paragraph:
If a unit has two or more types of ranged attacks
(including magical ones), it can only use one per turn.
.
One of the magical artefacts lets you use two spells per turn, once:
Myrddin’s Amulet of the Fire-heart - 10pts
Once per game, after using a ranged attack or spell, this unit may immediately use another different ranged attack or spell it possesses, against the same or a different target.