Is the idea to have a complication table perhaps .... I personally like how some 4e spells had repercussions when cast In particular those from the Malediction Invoker.
Malediction Invokers make for great thematic witches.
It could certainly be done via tables or it could just be done via a well-defined play agenda, procedures, and GMing principles (a la DW, AW, Blades).
What does "narratively it is not accurate" mean? There's lots of relevant fiction with unreliable spellcasting, and plenty of fantasy lit where casting in combat is not even an option (or at least, doesn't happen). The D&D version of a magic wielder (almost any of them) has become so much of its own thing that it seems to be warping what people see and write in the genre.
As far as "not fun" goes...well I suppose it wouldn't be for the caster players who are expecting to have everything work automatically, but...a) I've run other games where this was not the case with no problems and b) how is it any more disappointing than when a Fighter or Rogue rolls low damage or misses?
I was going to pose the same question, but this covers my thoughts pretty much completely.
Alright, so here was the last session I GMed in 5e. Of note:
1) This was an Epic Tier Aliens Invasion scenario with actual Far Realm "Grays", War of the Worlds type bio-constructs (like pilotable golems, but made of organics), and their mother ship. However, instead of harvesting bio-material, they were harvesting time, slowly turning back the clock of this prime material plane.
2) I didn't GM the preceding session or the climax of this session. The abstract that the GM gave me for the preceding session had it featuring 2-3 encounters. The climax of the session included the showdown with The Harvester; the alien entity that consumes the time that this world has accrued and assimilates it into its own consciousness, increasing its own god-like insight and knowledge. Again, I didn't GM it.
Here is how the gamestate was changed as play progressed until the session ended. Of note:
1) All enemies had Magic Resistance so Advantage on saving throws against the Wizard.
2) The Time Reaper - machine in the belly of the ship - caused local distortion that gave the PCs Disadvantage on attack rolls, ability checks, saving throws.
3) The Wizard had cast Foresight on the Fighter (their primary damage source) to offset Time Reaper.
Gamestate 1:
The 3 PCs are on the ground below the mother ship, having just defeated the initial welcoming party, which included single-man "hoverpods." Two hoverpods were intact after the encounter.
The Rogue fails one of the two rolls for his Disadvantage on his Investigation check (DC 20, Reliable Talent would apply, but wasn't sufficient to hit the mark as just Proficient, not Expert). The Diviner offsets it with the 1st of his 3 Portents and, due to the Wizard, the Rogue mans a hoverpod.
The Wizard fails his +11 Arcana at Disadvantage to start a hoverpod for the Fighter. So he just uplevels his Fly spell to 4th and the two of them fly up to the mothership.
Gamestate 2:
The PCs are attacked by the ship's defenses; a large number of small flying aberrations from the Far Realm.
The Rogue uses the flight, HPs and multi-attack of the hoverpod to engage them (which the Wizard enabled).
The Fighter has Fly and Foresight and wrecks them (thanks to the Wizard).
The Wizard (Warcaster, Resilient, and + Int for other two feats) uses Mirror Image and mobility (to ensure that Concentration isn't an issue for he and the Fighters' Fly), and Grease (his typical Spell Mastery spells) to effectively death spell several of the flyers (prone and they didn't have hover).
The Fighter uses his bow while the Rogue uses the hoverpods multi-attack and they win the day.
Gamestate 3:
Puzzle challenge to open the hatch. PC build neutral.
Gamestate 4:
The welcoming party. Mass Suggestion reduces the HUGE enemy force by 1/3. Forcecage cuts them by another 1/3. The rest are obliterated by the Rogue and Fighter.
They leave one alive to interrogate to attempt to locate The Time Reaper. They don't speak the same language (the Wizard doesn't want to burn a 3rd level for Tongues when he can...see below). The Fighter tried to pantomime what they were looking for and threaten the creature, but his Intimidate failed as he rolled really low (a 3 I think).
Gamestate 5:
Wizard casts Locate Object. This saved them 4 random encounter rolls during exploration so, while they ended up having an encounter on the way there (a defense system - equivalent of a Trap - that the Rogue was able to successfully deal with), it saved them another resource-depleting encounter (obviously no Long Rests, but Short Rests were fine) on this ship.
Gamestate 6:
The Time Reaper and the General. A parlay begins with the ship's commander and engineer. Tongues + Geas + 2nd use of Divine Portent to deal with the Magic Resistance and he's charmed. Fighter fails to destroy the arcane machine via Athletics and a nasty Time Warp AoE attack ensues on the PCs. Rogue with Disadvantage fails to destroy it via Expertise Thievery, but the Diviner turns his low roll into a 13 with his final use of Divine Portent and The Time Reaper is destroyed. Now, no Disadvantage for the Rogue and Wizard and the Fighter's Foresight equals Advantage.
Due to the charmed commander, they (a) get some relevant mechanical info for the combat to come with The Harvester, (b) enable a Short Rest, (c) they don't have to use their resources to fight him, (d) they avoid multiple further potential random encounters with a Take Me to Your Leader scene transition.
That is where the session ended. I didn't GM the climax.
It was a brutal indication of the disparate might of endgame Wizardry and Diviner's specifically (Portent is incredibly awesome in terms of thematics as an ability, brilliantly conceived, but unreal how powerful in terms of dictating or salvaging outcomes).
I'm sure people will decry this for bad scenario design, not "spotlighting the martial PCs", or not being adversarial enough against the caster PC, but I obviously disagree. This is exactly the sort of scenario that should be playing out in an Epic Tier game. All kinds of asymmetrical/multi-axis problems that, unfortunately as the system is constructed and as orthodox GMing dictates (orthodox insofar as the dictates of the regular GM of that game...which comports with the spirit of GMs I see on this board), martial characters struggle to deal with.
