No spell can have more casting specialisations than the sorcerer has ranks in his Sorcery skill. Of course with lots of spells, this should be an issue.

Creating new advantages is fairly easy since they modify an existing part of a single spell merely use the Spell Creation Guidelines from Supplement #3 and keep in mind that a single + or -1 modifier is worth two experience and a +/-1 modifier is worth five experience points. I do not recommend any higher.

Casting Advantages
These Advantages deal primarily with the techniques, methods, and modifications of the actual casting of spells.

Quick Casting (Two-point advantage)
By spending two experience points, a spell loses one off the casting time if it is a Slow casting spell. Slow 0 Casting Time spells are Combative and can be reduced no further.

Unfortunately, Quick Cast spells are weak and prone to disruption. The spells Height can be no higher than it’s Width.

(This is largely redundant because of Setekesh’s Will from Supplement #3).

Careful Casting (two-point advantage)
The sorcerer can squish the roll by 1, improving Height, reducing Width. Careful Casting can be taken twice.

Spell Advantages
Magic deals primarily with the effects of specialising a single spell. You spend the experience on one spell and it only affects that spell.

Dedicated Spell (Two-point advantage)
The spell’s casting Intensity is reduced by 1. A single spell can dedicated multiple times. Up to half of the spell’s Intensity can be reduced this way to the minimum of 1.

Tenacious Spell (Two-point spell advantage)
A spell still functions if its Width is reduced to 1.

Subtle Magic (Three-point advantage)
By spending three experience points, any attempt to detect the magic with Eerie being cast is hampered by a difficulty equal to the caster’s Coordination + Stealth pool. This is not rolled or a multiple action.

Resistant Spell (Five-point sorcery advantage)
All attempts to Counterspell a Resistant Spell has a difficulty equal to the sorcerer’s Stat + Sorcery pool.