The way this Build works is that you'll only be casting Incantations for your damage, and all of these Spells deal Lightning Damage. You can of course sub in other spells against Lightning Resistant enemies, but Lightning in general is a pretty good damage type.

Lightning Strike is your bread and butter spell that can AoE enemies in a line and does fairly good damage. It only costs 1 FP more than Lightning Strike, and it can be chain cast rapidly after the first cast, allowing you to melt Bosses easily with it. It does, however, start slowly so you'd be better off with Lightning Spear against enemies that are more aggressive.

Lansseax's Glaive does like a sweet in front of you of Red Lightning and it deals damage in an AoE behind that. This Spell has hyper armor allowing you to tank through most hits and still get the cast off and is good against large groups of enemies or very fast enemies like the Tree Sentinels, Night's Cavalry and Bloodhound Knights, as their movements are erratic, making it difficult to land more target spells.

Frozen Lightning Spear is decent ranged option which is good for setting Frostbite on enemies, which increase the damage they take. This can help with Lightning Resistant enemies in general.

Ancient Dragons' Lightning Spear is excellent against large enemies as it tends to hit them with multiple columns further boosting the damage. Make sure you cast this when as close to them as possible for maximum effect.