I suggest you don't, because on his own he is going to need some amount of protection while in a Temple Guard unit he needs basically nothing. Being a very expensive model and having his abilities quite expensive and limited, IMO you want as much into boosting his magic as possible. However you do save the points of a rather expensive Temple Guard unit by running him solo, so maybe it works out ok. The main thing I would put on him first is ethereal, then he cannot be hit by cannons and the like. Also hunters/fast cavalry will have a harder time bashing him up, but probably still could just with static combat res. Other than that, make him how you like him. That is about all the protection I would go for, make sure there is a unit or two of skink skirmishers near him for protection. Keep in mind that he won't get the LoS of a large target on his own, so you will either need to put him with your battle line or leave a gap for him to see through. A Slann should be able to cast every spell in a lore if he has the +1 dice per spell and all 6 spells, with that many spells running out it makes it tougher on your opponents defense but he needs to actually have targets for the one or two magic missiles.
i used a solo slann once. It wasn't that awesome ... i mean the only thing u gain is the points from the temple guards. I made him a 2nd generation slann of course and also i used the Totem of Prophecy so that i wouldn't autobreak from fear causing opponents, now you can choose terror. Then you should also take at least one skink priest so that while your slann is hiding you can shoot thru the skink's eyes. Plus u can use him as bait ... he will stand up in battle pretty good if you make him ethereal and if you use him right you will attract others to certain death from flank attacks of saurus or terradons.
if you put him between 2 units and run him a little behind them then he should be safe but watch out for tomb kings and dwarfs as their war machines are magical so they will still hit you but he will see pretty much fine and as to the not seeing as a large target i read it to mean whenever he cast not just in a unit but i don't know for sure either way he can only cast in his front arc but i have used him in this way but as i said i played him as seeing as a large target so if not he will be much more limited
You could make a pretty indestructable Solo Slann by having the following Disciplines: Ethereal Terror MR3 (not needed) All wizards within 24" ignore 6s (not needed) You can then add some offensive firepower in these ones: Knows all spells Free Dice Per spell So if you have a Solo Slann that knows all spells, gets the free dice, ethereal and causes terror (and fear). I think this is pretty indestructable with some offensive firepower. All for 425 points. Thats the build I would use for a Solo Slann. The only risk is losing to static combat res and getting run down; to sort this put a big mean unit of Krox or something nearby to help deter chargers (if the terror doesnt work)
You could always give him: Knows six spells Extra di per spell can only be hurt by magic Terror Items: Cupped Hands of the Old Ones Divine Plaque of Protection would protect from all ranged attacks with a 2+ Ward Battle-Standard bearer with War Banner, would keep something like Fast Cav from beating him in combat rez, and a crappy roll making him break. Personally, I love my expensive Temple Guard.
I run a Slaan without Temple Guard most of the time. Mainly just because I wanted to avoid the most popular build. I find that my army makes it very hard to get at him and most units really suffer when they do try. Just make sure you position him right so nobody overruns into him. There will be those games where it sucks, but for the most part I find it effective. One of my last games I got charged by White Lions and managed to see the whole unit off with my Slaan casting Flaming Sword of Rhuin on himself. Ethereal is fun.
Nice, I would have thought flaming sword is like bear's anger and only works on US 1 models, but just looked it up and it works for any caster. That is a pretty cool way to keep him safe. It does look like it is worth considering a lone slann with the points and special slot you save on temple guard, the problem I still think of is he is spending his allocations on defense rather than magic enhancement.
strewart, Flaming sword works on a slann it only work on the caster, no matter what US it is. Maybe you are thinking of Pha's illumination. A slann by himself i think is a good idea, 2+ ward vs shooting, regenerate, only magical attacks and maybe MR3, sets up pretty good defence. Especially if you do not have/or can not afford TG But for me, i would still put him in with a unit of saraus spears, making the slann the BSB with Totem of Prophecy (unit causes fear). Along with only magical attacks to protect him and character to take challenges Samuel