Read previous posts in this thread for some ideas on various spells for abyss/hell spell selection. Experiment stuff as you level.
Basics to Arcane: have at least a few different ways to instantly kill and as Pariah combo with Ability Decrease from Bestow Curse and Level Drain spells if Necro - (If you get Azzagrat 3 helm then combo BC with everyone in general - druids, clerics, even tanks; everyone loves you when a whole pack of mobs goes from hero to zero)
Common choices include some but not all due spell limitations of being a pariah: (Weird / Disint / Death (Cod/Wail) / PWK / UD2D / Sunburst / Horrid / Banish / Energy Drain / Enervation)
And a few different elemental damage types for variance in your setup
Common choices: Combust(Fire) Melfs (Acid) - Freeze Sphere/Polar Ray (Cold) Chain Lightning (Elec) Delayed Blast Fire Ball (Fire) Thunderclap (Sonic) - there are other elemental spells and soup variants which come in handy in LLs - experiment with them, but the ones mentioned are the cookie cutters you must pick some of them basically regardless of what else you do, even without Evoc focus. The soups are mostly for solo/lowman LL / Hell / Abyss specific shenanigans and abandoning your versatility temporarily for them, but experimentation to make things work for you is the pretty thing about being an Arcane (until lvl 80 sadness anyway).
And your physical picks in Evards, Flensing, Reverse Gravity and Bigbys Clenched Fist.
And utility spells - Weapon Buffs (at least have GMW + Fire + Magic covered!), Protection from Evil, Remove Curse, Shields for Fire/Cold imm, Gust of Wind, Break Enchantment, and so forth.
And of course pack a bunch of Mord Scrolls until Mord Rod from Demishop + electrifier / Breach Spell / Mord Spell (if you must, in general will be hard to fit but if you can go for it at least temporarily in case of emergency)
^Some form of these is highly recommended in most areas in the endgame.
Pariah Specialities to keep in mind: Pariah has a hard time fitting everything so pick your poison. Strong weapon buffs (GMW + Magic + Fire + Elec - can be hard to fit all of them, but at very least GMW + Magic + Fire recommended. Super Disintegrate machine; massively prominent Bestow Curse, High SP and DC on Flensing / Reverse Gravity / Clenched Fist - and the special Shapechange which is mostly used for AoE Stoning and AoE Pickup in case of emergency, others seemed wasteful but experiment and see if you can pull them off and use your entire spell selection well.
The thread has some outdated stuff as there was a significant nerf on Flensing and Reverse Gravity; as such Bigby Clenched Fist is now more relevant since RG/flensing won't cut it on their own anymore, and for LL purposes Rg might even be a bad choice, and in Limbo it won't work at all. Should consider dropping Sunburst or Horrid for Clenched Fist as in original spell setup and deal with the old way - damage or let another caster deal with it. Sunburst is a candidate to drop since divines cover it, but then again horrid doesn't have as many uses in the game.