Linking spells

[Hilary]

I would like to make a spell that allows spell casters to link their spells. The obvious example of this would be Silent Image.

If a spell casters casts 'Spell Link' on a spell caster within range, then casts a spell before the Spell Link's duration is up, that spell will be handed off to the targeted spell cast. The targeted spell caster must have the same spell active (cast and the duration has not lapsed). The targeted spell caster then gains control both spells - as if they were a single spell with a larger area of effect or similar.

[Cicciograna]

In 3.5e there was something similar, it was a Cleric spell named Imbue with Spell Ability (http://www.d20srd.org/srd/spells/imbueWithSpellAbility.htm). It was not exactly what you describe, it transferred some spells prepared by the caster to a target, as well as the ability to cast them. You could take that as a starting point for your new spell.

Since it is not the full spellcasting capability that is transferred, but just the control of the spell, I'd say that you might start lowering the spell level.