[Taqwus]

Soul Vortex gives the caster a life-draining aura for the duration of the battle; every turn it tries to drain life from those in nearby randomly-chosen squares, including friendlies.

Ghost Riders is pretty brutal; it's a good argument for building castles to protect your temples. Conj 9 is strong for death nations, with both Ghost Riders and Tartarian Gate.

If you want to try an assassin pretender right out of the gate, try Mictlan's Lord of the Night. He also starts battles with a couple of Fiends of Darkness, which helps make things even more unfair.

Regarding searching, I suggest using the path-specific searching spells as soon as you can; it takes one mage turn instead of two (one to arrive, one to search) and can be easier than getting a level-four mage. For certain paths this is easier than others, e.g. Astral Probing, Dark Knowledge require only one level of astral or death respectively.

For something different, try R'lyeh. The Void Gate is like a wacky slot machine that can feeblemind or kill you, but also might give you Vastnesses, Greater Othernesses, and Things that Should Not Be. For observing the joy of Orb Lightning spamming, try Pythium with a large communion...