**The key idea:** A spell says how many actions it takes, its range and targets, and whether you roll a **spell attack** or the target makes a **save**. Not every class casts spells.
## Cast a spell
1. Pick a spell you can cast and read its **action cost**, **range/area**, **targets**, **duration**, **traits** and any costs or requirements.
2. Pay the listed cost: a **spell slot** for a ranked spell, a **Focus Point** for a focus spell, or **no slot** for a cantrip.
3. Follow the spell's **defence**: your spell attack vs AC, a target's saving throw vs spell DC, or another specified resolution.
4. Apply critical success/success/failure/critical failure results exactly as printed. If a save says **basic**, the usual no/half/full/double-damage pattern applies.
Spell attacks have the **attack trait** and can suffer the multiple attack penalty. Spellcasting itself does not automatically do so; read the individual action. *(Player Core, pp. 294–300, 394–395.)*
## Which magical resource?
| Resource | What to remember |
|---|---|
| **Spell slot** | Normal ranked spells expend slots of a suitable rank. Prepared and spontaneous casters manage them differently; follow your class. |
| **Cantrip** | Cast at will; costs **no spell slot**. Normally automatically heightens to **half your level, rounded up**. |
| **Focus spell** | Costs **1 Focus Point**. Focus spells normally automatically heighten like cantrips. |
| **Focus pool** | Maximum is the **smaller of 3 or the number of focus spells you know** that use the pool; refreshed during daily preparations. |
| **Refocus** | **10-minute exploration activity**, restores **1 Focus Point** if you have a focus pool; repeat if you need more. |
| **Innate spell** | Granted by ancestry, heritage, item or similar source. Its granting ability says how often you can cast it; innate cantrips are at will. |
*Source: pp. 294–298.*
## Sustaining and ending effects
- **Sustain [1 action]:** continue one effect with a sustained duration (or gain its listed Sustain benefit). The duration normally extends until the end of your next turn.
- **Dismiss [1 action]:** only effects that explicitly allow Dismiss can be ended this way.
- **Detect Magic / Repeat a Spell:** during exploration, use the relevant exploration activities rather than taking repeated encounter turns. See Sheet 04.
- A spell that is **disrupted** generally loses its effect and expended costs. Traits and circumstances determine whether it can be disrupted.
*Source: pp. 298–300, 406–407, 411, 430–432.*
## Quick comparison
**Example A:** You cast a spell that requires a **spell attack**. Roll d20 + your spell attack modifier against AC.
**Example B:** You cast an effect that requires a **Reflex save**. The target rolls Reflex against **your spell DC**.
**Example C:** You need to keep a sustained effect active next round. Budget **1 action to Sustain** if the effect still requires it.
**Official sources:** *Starfinder Player Core*, pp. 294–300, 394–395, 406–407, 411. **See also:** Sheets 01, 04, 06 and 08. This entry does not replace class-specific spellcasting rules.