Some examples of powerful magic IMO
- ohk spells(finger of death on nwn1/blood boil on vtmb/disintegrate - arcanum)
- Town nuking spells(hailstorm on g3)
- dominate spells(Dominate monster on nwn)
- army summoning spells(army of darkness on g1/g2)
- "freezing" spells(ice lance on g3)
- Teleportation spells
On Baldur's Gate/Neverwinter Nights, Finger of Death OHK enemies who fails a save. Phantasmal killer is a tier 4 spell that does the same but allows a WIS and a FORT save to OHK the enemy. On non TTRPG based games, Gothic 1 had Death to the undead(ohk any undead) as a circle 4 spell. It has a high charging time but allow no saves. VtMB has blood boil that not only OHK most targets but also transform then into blood grenades who damages nearby enemies.
Arcanum had a more powerful version. Disintegrate. It not only can be used on living but can also be used on objects, allowing you to disintegrate heavy fortificated doors and access areas that you would't had access
About army summoning spells, Gothic 1/2 had it and 3 limited to one instance of summoning, except by army of darkness, you can't have multiple summons. Pathfinder Kingmaker has animate dead which creates d4+2 undeads or 3~6. Each skeleton is if i remember correctly CR 7(cr = challenge ratting). You can even summon a Thanadaemon which has the same CR of a adult dragon(cr = 13),
Charm AND dominate spells are a necessity on ToEE. Mainly once you reach the temple. Charm is a tier 1 spell who made possible to solo icewind dale. Without that spell, there are no way to solo IWD on low levels as a arcane caster.
Might & Magic VI has a dark magic spell called Armageddon. It deals 50 + Dark Magic skill damage(a lot) on everything on the map(including allies and NPC's and your own party). Dragon's Breath also is so powerful that i once time OHKilled a high level enemy and my party with the AoE damage because i miscalculated the distance. And M&M VI has finger of death too that can OHK anything that is not MAG immune.
Enemy "halting" spells like Bigby's crushing hand on NWN1 are amazing too. Ice Prison on Pathfinder Kingmaker is my favorite 5th tier spell by far. On Gothic 3, Water Mages with Ice Lance can prevent almost all enemies except bigger ones with high cold resistance from even doing any damage. On G3 i love to freeze enemies and cast ice explosion on then.
Once you reach end game and learn HAILSTORM, you can do pretty dope things, like nuke a orc army at distance
What about shapeshift spells? On PF?KM you can even assume creature forms like a SILVER dragon and raise a thanadaemon army
Teleportation spells are another amazing thing. On arcanum, you can travel everywhere. On M&M VI, you can place beacons and teleport back any time. Morrowind had mark/recall spells and divine intervention too.
What do you think about this games with really powerful magic?