I'm aware of the hotly debated "...normal limit of one spell per round" text from the rules on magic casting time. Assuming that this doesn't mean anything substantial, however, what is a theoretical ceiling on the number of spells one can cast or directly cause to be cast in a single round? I'm only concerned with spells per round from the perspective of the caster, not apparent time, so time stop doesn't count. I'm willing to consider any combination of other spells, magic items, class abilities, etc.
Four (Base rules)
Five (Including hero point rules)
Ten (Or unlimited) (Including hero point and mythic rules)
(In one round)
- Cast a spell via a standard action
- Cast a spell via a swift action (Quicken spell et al.)
- Cast/activate a spell from a contingency
- As a magus use your offhand to attack with a weapon and activate a spell storing weapon to cast another spell, since you can use Spell Combat to cast one spell and attack at the same time.
- Cast a spell by expending a hero point.
If you are using Mythic Tiers then you can cast/trigger Six spells on yourself with contingency, this is because Mythic contingency allows you to activate 1 contingency spell (on yourself) plus half your mythic tier. Maximum mythic Tier is 10. So you can use mythic contingency to activate 6 spells at once, plus the others.
Or you can activate/cast a theoretically unlimited number of contingency spells as the range of the spell with Mythic increases to touch, allowing you to place contingency on any person you touch.
Ie if Wizard Bob spends a year using Mythic Contingency casting Beast Shape on all his minons which is activated when he shouts "By the power of Greyskull" then his entire army can be turned into battle cats if they're in earshot of him.
Bonus extra pointless spell!
Other wackiness is the use of Heroic Finale which allows:
With a flourish, you immediately end the performance, and one creature within range affected by your bardic performance can make a move action or a standard action of their choice.
Since you can yourself be the subject of your own performance you can theoretically use it on yourself but it's pretty pointless as you're spending a standard action to get another standard action - but it is another spell!
I'm discounting someone else casting this on the character as it activates on their turn and it's only the caster using it.
You could also argue that you could chain-cast Heroic Finale on yourself to cast as many spells as you have 4th level (and above) slots (as long as they're Heroic Finale!) but since the spell states "you immediately end the performance" you'd only get one spell out of it in my book as the bardic performance has ended.
It depends on what spells you are trying to cast. Some spells have an extended casting time that can last for several rounds(such as the Masterwork Spell[can't remember the real name]). However there are both normal spells(like Burning Hands) and quick spells (such as Cheetah Sprint). Since you have 1 movement action, 1 standard action, 1 quick/swift action and infinite free actions(like quick draw), you could cast an unadjusted amount of 2 spells. For instance, you could TECHNICALLY cast Cheetah Sprint on yourself, run across a map while quickdrawing and dropping individual caltrops, and heal someone near the end of your run (if there was such a thing as spellcasting at the end of a charge/run)