Definitely something to consider here -
While your combination can blast your opponent to smithereens, there are other options, and some may be more worth the while.
Lore of Light is good if you're running a Slann Magic heavy list but with lots of blocks of Saurus and other hard hitters. If you're running a squishier kind of army and a Slann this Lore might be the wrong pick for you.
Lore of Light
Initiative 10, Weapon Skill 10, +1 attack and Always strikes first from two spells that can be cast at moderately low levels? Hell yeah. Dump this on your Temple Guard at signs of trouble or when you sound that battle horn and charge into the fray. Yeah, that's right Grave Guard, Chosen, Grail Knights and Phoenix Guard there's a new bad boy in the house.
Not to mention the Lore's offensive spells absolutely put the hurt on demons doubling the strength of the hits and number of hits. Its almost as if GW gave us this Lore indirectly for the Lizardmen to use...Powerful against demons, good for buffing slow models and low weapon skills? Very fishy. And not to mention some of the other debuff spells for opponents can be handy in a tight spot. Overall I think the best Lore to use if you have a heavy infantry - Slann type list.
People with those squishier kinds of lists with a Slann/Lone Slann personally I believe Lore of Life is the one for you...
Lore of Life is jam backed with buffs and healing abilities that drastically change a battle by filling it with stone hard soldiers, or healing a wound or two off a hero, or even pulling a leaf out of the Vampire Counts abilites and bringing back some soldiers! Hell, you can even protect the Slann completely from miscasts! What's not to love? Maybe the lack of offensive spells. Sure Dweller's Below is a army composed of low Low strength models a nightmare, and Awakening of the Wood only super effective if you’re casting at something near the woods. Sure Light may not have that many offensive spells, but the thing is most of the Lore of Light’s spells affect something to do with combat. Life is defensive combat, which you DO NOT WANT when you don’t have many blocks of Saurus or Kroxigor infantry. Trust me. The strategy with Life is to sit back and let the enemy come to you while protecting and healing your units with buff and healing spells, and protecting your Slann from miscast damages with Throne of Vines. Usually you’ll want to run this list with a Engine of the Gods and keep the Slann near the Priest so whenever he takes a wound the Lore attribute will be able to heal him up. In 8th edition it’s usually helpful to pay the 40 points for a 4+ward save on the Skink Priest, allowing him to drop that Burning Alignment as long as possible.