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Chapter 10: Magic and Spells / Casting Spells

Concentration and Interrupted Spells

Source Starfinder Core Rulebook pg. 331
To successfully cast a spell, you must concentrate. The length of time you must concentrate to cast a spell is specified in the Casting Time entry in the spell’s description. Your foes can interrupt your spellcasting in a few ways, as described below.

The concentration required to cast a spell is sufficient to cause you to briefly lower your defenses. If a foe threatens the space you are in, casting a spell provokes an attack of opportunity unless the spell specifies otherwise. For more on attacks of opportunity, see page 248.

Normally, you can concentrate even in a distracting situation, but if you’re casting a spell and you take damage from either a successful attack that targeted your AC or from an effect that you failed a saving throw against, the spell fails.

You are most at risk of taking damage while casting when a spell’s casting time is 1 round or longer, you have provoked an attack of opportunity, or a foe readied an action to attack you when you began to cast. However, if you are taking ongoing damage (such as if you are bleeding or on fire), your spells are not disrupted in this way.

If you ever try to cast a spell in conditions where the characteristics of the spell can’t be made to conform, the spell fails. For example, if you try to cast a spell that targets a humanoid on a non-humanoid, the spell fails.

Concentrating In Harsh Environments

If you attempt to cast a spell in environmental conditions that make spellcasting impossible, the spell fails. You can typically cast spells in bad weather or when your ship is making tricky maneuvers, but at the GM’s discretion, if you are subject to extremely violent motion (such as an earthquake) or extremely violent weather (such as a hurricane), you can’t concentrate to cast spells. For more information on environments and their rules effects, see page 394.