The Sorcerer-Prophet is a Wizard Lord (Death, Fire, Metal or the new Lore of Hashut) with built-in armour (4+ save, 5+ ward vs. Flaming Attacks) and built-in magic weapon with one of six random effects. The +1 to channelling and +1 to dispel will be the valuable ones, to my eyes. The breath weapon might be good for a laugh on a mounted Prophet. Possessed is a bit Chaos (one in six chance of doing an unsaveable wound to himself with every attack) but could be decent for thumping high-Toughness low-save targets. Hatred and Multiple Wounds aren’t exactly bad, but the Sorcerer-Prophet doesn’t exactly have superb Strength or Attacks scores; not enough to be giving proper combat Lords a run for their money. Still, as a whole package it’s not bad, affording your Prophet the chance to take a magic shield for a decent save, and allowing him to smack annoying Ethereal models around the face and potentially be better at spellcasting.
There are a few weapon options available; there’s a pistol (cute, but I think a magic shield will be more use), a ‘naptha bomb’ (awful range, mediocre Strength, fifteen points down the shitter if you ask me) and the Blood of Hashut, a one-use item which replaces the Prophet’s melee attacks with that Searing Doom spell from the Lore of Metal, hitting one enemy d6 times on a 2+. A bit niche, but could be good if he’s tied up fighting one of those highly popular 1+ save run-out-and-tarpit characters.
The Prophet has three monstrous mount options. There’s the budget Great Taurus and the notably more expensive Bale Taurus; the difference being the Bale version’s T6 and W5. Neither Taurus is particularly well-protected for a Large Target; no Ward Save, not even Scaly Skin. That said, they’re not bad in a punchup – a S4 Flaming Breath Weapon, the de rigeur Thunderstomp, Blazing Body, and WS5, S6 and A4 on top of that. While they are large, cannon-bait models, they regain d3 wounds if you target them with a Lore of Fire augment spell and, more to the point, they have Blazing Body. If I understand matters correctly, the -1 to enemy To Wound rolls means that bows can’t actually hurt the Great Taurus, while crossbows and handguns can’t actually hurt the Bale Taurus, since it’s a -1 on the die roll and those weapons need sixes to wound the big bullies. Even cannons and other such nonsense will need a 3+ rather than a 2+ to hurt them; not much, but every little helps!
The other option is the Lammasu, making a guest appearance from Storm of Magic and sitting nicely in between the two Taurus variants in terms of cost. This thing has inbuilt Magic Resistance, nullifies magic weapons on anything in contact, and is a level 1-2 wizard in its own right; unlike the other options in the Legion, the Lammasu can deploy the Lore of Shadows, for which it swaps out Metal. What this means, in theory, if you don’t mind putting all your eggs in one basket, is that you can quite cheerfully not buy any wizards from the Heroes section and rely on your Prophet and his beard-faced steed to do all the spellslinging. Without Blazing Body it’ll be more vulnerable to shooting than the Great Taurus, but it can join combat alongside other units without setting them on fire.
So far, so good. The other option is Drazhoath, the leader of the Legion of Azgorh. A level 4 Prophet with an extra point in WS and W, on a Bale Taurus with a S5 breath weapon, Drazhoath comes with a 5+ Ward save, a +1 to cast spells, and the capacity to wound anything in the game on a 4+. He also has some interest in getting up close, since killing an enemy Wizard gives him an extra +1 to cast, and passing a Ward save in close combat causes a S2 hit on whatever inflicted them. Finally, Chaos Dwarf units within 12″ (and that’s only Chaos Dwarf units – remember, the army is the Legion of Azgorh, not Chaos Dwarfs, so Hobgoblins don’t count) get a +1 to their combat resolution. At 570 points (a regular level 4 Prophet on Bale Taurus is 525) I think he’s worth a go. You could probably build a slightly more resilient, or slightly more casteriffic, or slightly more competent-in-melee Prophet, but I doubt you could build as effective an all-rounder for his price.
Personally, I’d give Drazhoath a go if I were going to take the Taurus. A Prophet on Lammasu runs to 460 before upgrades, so you can juuust sneak him into a 2000 point army. Meanwhile, a pair of level 4 Prophets with no other kit will set you back exactly 600 points, i.e. exactly your Lords allowance in a highly popular game size. I wonder if Mr. Bligh reads Yes The Truth Hurts?