This spell allows you to witness two divergent decisions and choose which to pursue. Upon completing this spell, you must immediately choose two other different spells that you could cast at that moment and that each have a casting time of 1 standard action; these spells take effect simultaneously, and you must track all resulting effects, areas of effect, saving throws, and other outcomes separately as if each had been cast normally and the other spell had never happened. Once you’ve seen how each spell resolves, you must choose which version of reality occurred, expending the standard action, prepared spell, and material components as necessary. The other spell’s results are ignored and do not require an action or expend the prepared spell, spell slot, or material components. If the targets of the spell you did not choose expended any resources or effects to resist your spell, those resources or effects are also not expended.
The obvious intended use of this is to cast one or more high risk, high reward save or lose spells at high level to increase you odds of either a big win or a save second best outcome. But what else can we accomplish outside of combat that might otherwise be risky, but can be mitigated by using Temporal Divergence and some throw away cantrip as a backup option?
Two occur to me:
1. Mage's Disjunction to destroy an artifact and preserve your spellcasting ability. Succeeded at destroying the artifact but failed the Will save to keep your spellcasting ability? No problem, try again. Expensive, given the number of times you'll have to cast MD on average to even succeed at destroying the artifact, but maybe worth it to you if you're well funded, need the artifact destroyed, and won't accept a 1/20 (or 1/400) chance of becoming a commoner.
2. Dangerous Wish. Cast Wish, see if there's some unforseen backlash or twist, don't choose it if that happens.
What other 1 standard action spells are there with big risks that this trick might work for?
Cast long duration spell on the one hand--Magic Vestment, for example--and some instantaneous cantrip on the other.
Congratulations on figuring out a 100% safe way to scout an area and predict the future! Track exactly how the Magic Vestment spell works out as you wander a dungeon for a few hours, discovering the placement of traps, treasure, and monsters, then scuttle that spell and cast the cantrip instead. You'll also find out what big events--things that your spell choice won't change--happen in that time.
The "If you cast this spell and do not or cannot immediately follow the instructions described above, this spell has no effect" line might be meant to disallow this sort of abuse, but I find it awfully unclear.
Cast long duration spell on the one hand--Magic Vestment, for example--and some instantaneous cantrip on the other.
Congratulations on figuring out a 100% safe way to scout an area and predict the future! Track exactly how the Magic Vestment spell works out as you wander a dungeon for a few hours, discovering the placement of traps, treasure, and monsters, then scuttle that spell and cast the cantrip instead. You'll also find out what big events--things that your spell choice won't change--happen in that time.
The "If you cast this spell and do not or cannot immediately follow the instructions described above, this spell has no effect" line might be meant to disallow this sort of abuse, but I find it awfully unclear.
That doesn't work, the "outcome" of the spell is that you get a buff and it "resolves" once you cast it. Once you see the buff successfully appear (or not, for some odd reason, like a successful counterspell) you have to choose and you're locked into that.
Some divination which might alert the enemy perhaps, like greater scrying? Scrying sensors aren't that hard to spot, and countermeasures exist. Triggering those countermeasures lets the target know that someone's tried to scry them at least.
That doesn't work, the "outcome" of the spell is that you get a buff and it "resolves" once you cast it. Once you see the buff successfully appear (or not, for some odd reason, like a successful counterspell) you have to choose and you're locked into that.Cast long duration spell on the one hand--Magic Vestment, for example--and some instantaneous cantrip on the other.
Congratulations on figuring out a 100% safe way to scout an area and predict the future! Track exactly how the Magic Vestment spell works out as you wander a dungeon for a few hours, discovering the placement of traps, treasure, and monsters, then scuttle that spell and cast the cantrip instead. You'll also find out what big events--things that your spell choice won't change--happen in that time.
The "If you cast this spell and do not or cannot immediately follow the instructions described above, this spell has no effect" line might be meant to disallow this sort of abuse, but I find it awfully unclear.
Contagious Suggestion, then. Or a long lasting aura that others have to save against.
Or, ohmigod, phantasmal force. You won't know for sure who might fail a save against it until you stop concentrating.
Hmm... here's an idea. Whenever you leave an erratic time demiplane, you roll percentile dice to determine the corresponding amount of time that has elapsed on the material plane. If the result of that roll is considered an "outcome" of the plane shift spell used to leave, then you could use temporal divergence to game the system, only leaving when you obtain a favorable conversion rate. With this trick, you could consistently spend days in your personal erratic time demiplane while only rounds pass on the material plane. And for high-level spellcasters, days of free preparation time is basically godhood.
You could prepare that OP combat spell that your GM allowed you to create but you never used because it had a 24 hour preparation ritual