I don't write much on tactics, a WFB strategy savant I am not. Go see Bringer of Victory for that department. However, a recent BOLS article about Lord choices made me face palm. The article was suggesting some "interesting" Lord level character combos. One suggestion was running two Slann. One would have Lore of Life with Focus of Mystery (giving him loremaster). The other is packing Lore of Death with Focus of Mystery and Focused Rumination (+1 power die per casting roll). As a Lizardmen player, I'm all for all-glory-to-the-hypno-toad, but this suggestion really stuck in my craw.
Problem 1: you will not have enough power dice per magic phase to justify dropping 600 points into these two models. Saturday I played a 2,500 point game with my lizards against a Night Goblin army. It was not a hyper-competitive game but the example will illustrate this point nicely. My Slann ran Lore of Life with loremaster and +1 power die per cast. I also had a Skink Priest riding an Engine of the Gods. The gobbos did bring a Staff of Sneaky Stealing to the party, which lost me a power die per turn (great item for magic defense), but did I roll hot for channeling all game, giving me a bit of a boost to my casting pool. The Slann burned through the power dice like a meth junkie on a binge. I cast only one spell with the Skink the entire game. Imagine two Slann with full access to two magic lores and their competing demands for power dice. With two Slann you will not have enough power dice to use each one's magic lore to full effect even with Rumination giving you an extra die per cast. Do you really need to have both Dwellers Bellow and Purple Sun in your arsenal? The points spent on Slann number two will be better spent elsewhere, particularly given your expensive Saurus infantry. In fact, the cost of the second Slann is more than a 20 model block of Saurus Warriors with full command.
Problem 2: these two Slann are under prepared, and I like my frog legs well seasoned. As listed above, these two will cost 600 points, so you can squeeze them in to a 2500 point game. However, one of these guys has inadequate dispell protection. The frog with Life will have Throne of Vines but what about the other? He'll need Cupped Hands of the Old Ones, which you takes you over the 25% cap on Lords for a 2,500 point game. Heaven forbid the unprotected Slann goes nuclear next to or inside of a unit of expensive Temple Guard or Saurus Warriors (which as pointed out above, you will probably have less of). The above two Slann would probably both need Rumination to stretch your power dice as well as Cupped Hands on the Lore of Death toad. You'll probably also want to make one of them your BSB. This takes us to 720 assuming you don't buy a magic banner.
I'd be hesitant about paying this many points for two models in a 2,500 or 3,000 point game. I'd also be hesitant about buying an extra chunk of pewter that I wouldn't get much use out of. But I could be wrong and if anyone has tried something similar and knows better, I'd be interested in hearing about it!