FAQEdit clarifies: What are the game impacts of rolling for spells at the end of the turn you finish concentrating? Why was it changed?
The rule refers to the active part of your turn. If you cast a one-second spell, you take a Concentrate maneuver and immediately roll the dice. Only those who are waiting – and persistent, ambient effects – can interrupt. Specifically, you do not wait until others have acted before you roll.


p. 11 of GURPS Psionic Powers introduced this variation, also mentioned on page 11 of Power-Ups 8: Limitations.

as highlights, there is a thread on it at with a mention from Kromm


One thing my players like is my house rule allowing All-Out Concentrate and All-Out Ready, sacrificing all defenses for +4 to the eventual task. Power Blow is at -5 after a turn. It can be worth spending that turn doing AOC to get +4 and make it -1, which is useful even at low skill. Personally, I find that more flavorful and truer to the source material . . . somebody who's squinting her eyes shut and making wax on, wax off motions with her hands should be defenseless while "charging up" the ability. But all of that is house rules and opinions only.

GURPS Compendium 2Edit


If one combatant is taking the Concentrate maneuver, his opponent must win a Quick Contest of IQ in order to perceive that his foe is concentrating.




The only maneuver that shouldn't be obvious is Feint. Everything else is meant to be stated openly.
All-Out Attack would be zero-risk if it weren't obvious, and Concentrate over multiple seconds wouldn't be the drawback that the rules for spells and powers assume it is if enemies weren't aware of it.

See alsoEdit