Fast cast
Fast cast is how you stop spending two minutes buffing before every fight. You put a set of spells into a slot once; from then on one button casts the whole set.
You get ten slots, each holding as many spells as you like, and each one you fill appears on your radial menu as an ability of its own. Give the slot a name and that is the name the ability wears
no meaningful limit on uses.
It is worth saying plainly what it is not: fast cast does not give you spells, slots or uses. It casts what you already have, in the order you chose, and every spell it casts is spent out of your own allowance exactly as if you had cast it by hand.
Setting a slot up
Open it from the Player Menu. Pick a slot, and you are looking at your own spells - filtered by class, by spell level, and by metamagic. For a class that memorises, you can show everything you know or only what is currently memorised, which is usually what you want when you are filling a slot for tonight rather than in general.
A spell you add remembers three things: which class casts it, what metamagic it carries, and which domain level it goes off at when it is a domain cast. So a cleric who wants an extended version of one spell and a plain version of another gets exactly that, and a multiclass character's spell is always cast by the class you picked.
Close the menu and the ability appears. Put it on your quickbar.
Fast and slow, and why it matters
Not everything in a slot goes off at once, and the rule is simple:
- A spell that can be cast on other people is cast instantly.
- A spell that only works on yourself is queued and cast at its normal speed, one after another.
- Summons and polymorph are always queued, and always last.
So a slot full of group buffs lands in a moment, and a slot full of personal buffs takes about as long as casting them would - but you only pressed one button, and nothing is forgotten or cast in the wrong order.
In combat, nothing is instant. The moment you are fighting, every spell in the slot is cast at normal speed, group buffs included. Fast cast is a tool for the thirty seconds before a fight, not a way to rebuff in the middle of one.
Two things that will catch you out
One polymorph per slot, at most. Changing shape clears every queued action, so anything stored after a polymorph is thrown away without a word. Put the polymorph in its own slot, or make it the only one.
A dead ability on the radial menu. If you empty slots in a different order from the one you filled them in, the base game can leave an ability behind that does nothing and will not go away. Log out and back in and it is gone.