If you like to punch people, consider using buffs, even a skink priest using Luckomancy can swing the tide in your favor, Portent of far and Second Sign of Amul help enormously in fights, maybe as much as a hero in some cases. Some of the other buffs the Slann can pull out are also beastly, Lore of light can cause WS 1, and Metal can give -1 to Armor save, Hit and wound. Getting those debuffs and buffs can let even skinks fight even on swordsmen, and saurus can be one upped over chaos Warriors.
You can just Mass up on flaming pew pews and throw lightning and fire and comets at people, in this case, give all your skink priests at least one power stone, that way they can threaten to cast comet, or work two spells in one critical turn, typically right before a melee.
What I like to do is go for spells that don't pew people to death, but spells that just say "I win" if they go off. The wolf hunts, Unseen Lurker, Pit of Shades, The beast cowers, or even Doom and Darkness can just say "you lose". A slann also lets you hate draft, facing a gun line? Take lore of life, spam rainlord on cannons and gunners and hide behind a unit that has the howler wind cast on it and abuse the fact that they'll be on a hill for master of stone.
Ancient stegadons are nice too, but whether you use them or not is up to you, if you are all out magic then sure, use one to make heavens easier, maybe even have a slann take heavens and just predict a lot of stuff. Heavens can get stronger if you use the Skinks to cast portent on a Slann and use second sign of amul as well, with a great number of re-rolls powered up the lightning spells can really hurt, though the same is true for any damaging lore, Rule of burning Iron re-rolling ones? That'll hose someone for sure.