Best part of magic in 4 was the spell creation, best part of 5 was the different delivery methods for the spells. Low level streams, persistent AoE, target chaining, the wall spells, the runes that acted like mines. It wouldn't be too hard to combine the 2. Hell, you could even work spell weaving into actual combat rather than menus if you get creative enough. The trap plasmid from bioshock that has different effects based off what follow up plasmid you cast comes to mind.