These next are two spells which indicate the complexity required for Hermetic magic in Ars Magica to create permanent magical creatures, as proposed through a discussion. This is not based upon a RAW guideline, rather some very logical forum discussions.
It’s worth noting that creating a normal wolf permanently is far easier; both these spells create creatures which could exist in the setting. If used in a saga I suggest that each spell become far more specific in terms of beast description, demeanor, and powers. A creature of the magic realm they should be closer to the idealised forms of their animal types.
Conjure the Majestic Wolf
Creo Animal 55, R: Touch, D: Momentary, T: Individual, Ritual
An adult wolf is created with 10 Magic Might and a small selection of powers, such as supernatural stealth and resilience. The magical beast is permanent and may have Cunning or Intelligence. The creature will have a personality and traits of its own and is under no obligation to serve the caster.
(Base 50, +1 Touch)
This idea came from the Atlas Ars Magica forums thread:
If we look at the ‘Conjure the Walking Dead’ Ritual Spell from Hermetic Projects (Pg 117), it explains that the base level for creating a magical human is level 45; coincidentally the magical might of the revenant (pg 116) is 9; a simple ruling could be made that the magnitude of the spell is the amount of Magical Might that the creature would have.
Base level 50 for magical animal would make a magical might 10 creature, with +1 magnitude for +1 Magical Might
i.e a magical might 15 lion would be: Creo-Animal 80 ritual
(base 50, +1 Touch, +5 for higher might) with requisites for the powers that the lion has, Imaginum/Aurum for a super loud roar etc.