4000 points? 5,000 points? Never? I know winds of magic provides a ceiling to power dice, but eventually another lore or back up caster that's not a skink might become tempting. I don't know what level that would be but I figured I'd take one normal Slann and one SC Slann (probably Kroak rather than Maz) rather than two ordinary Slann. Kroak could provide some straight forward destructive power while another Slann could throw around buffs or hexes.
Ive been playing around with 2 slann at 2500. Your casting is not as guaranteed as taking the one super slann, but its still very effective.
At 4k, it is a viable choice. I usually take a life and death slann at that level. Death because of the potential added power dice from wounds caused. I will never try to cast the Purple Sun spell though. Every time that I have EVER used it, it misfired and killed my death slann. I use him to snipe characters.
I'd take Double Slann at 3k, it's pretty much ideal at that point level. Below that, one Hypno-Toad will be enough for most armies, especially with a cheap Old-Blood attached to his TG bunker to challenge enemy assassins. Death is kinda risky TBH, and it's one-dimensional (it kills stuff). It has no buffs, like 2 hexes, and the ultimate is often quite suicidal to cast. Shadow will nuke stuff just as easily, it can't backfire the way Purple Sun does, and the Lore itself brings a lot of useful buffs and hexes ('Pit of Shades' isn't even it's ultimate, 'Mindrazor' is scary as hell on Temple Guard). And hey, Shadow lets you re-create the old Jaguar Scar-Vet/Old Blood build, but you don't have to take a useless item to unlock it (which means more delicious magic armour/weapons on your hero).
At the 2011 etc, there were actually quite a few lizard players running double slann at 2400. No idea how they did, but the ETC normally has high lvl players
Yea 2400 and up I would go double slann every time for a competitive game. Light/life slann coupled with a banehead death slann.