Room for Maneuver?

[munin]

Assuming that concentration is more like making a ranged attack than a melee attack (you're not directly engaging with an unpredictable opponent), I'd suggest a simple -2 to all success rolls having to do with that move and concentrate (M+C) maneuver: any success rolls on that turn, and any success rolls for anything you used a M+C on.

For instance, usually you have to make a Will-3 roll to maintain concentration if injured (et al.), but you roll against Will-5 after taking a M+C. If you concentrate for multiple seconds, then the penalty only lasts as long as you keep taking M+Cs -- taking a Concentrate maneuver resets you back to Will-3 for instance -- but the -2 penalty still applies to the final success roll for which you took multiple Concentrate and M+C maneuvers.

Let's try a write-up and see if that helps:

tabMove and Concentrate: Move as described for the Move maneuver (p. B364) while concentrating on a primarily mental task (casting a spell, using a psi ability, etc.). This imposes a penalty of -2 on your success roll for that mental task. When using an ability that requires multiple seconds of concentration, you may alternate between Move and Concentrate and other Concentrate maneuvers, but the -2 penalty still applies to the final success roll. If you are forced to use an active defense, knocked down, injured, or otherwise distracted before your next maneuver, you must make a Will-5 roll. On a failure, you lose your concentration and must start over.
tabMovement: As described under the Move and Attack maneuver (pp. B365-366).
tabActive Defenses: Any. However, it interferes with concentration as noted above.

Since All-Out Concentrate (GURPS Psionic Powers, p. 20) must be taken for the entire concentration, there would never be any reason to combine All-Out Concentrate and M+C maneuvers, so no worries on the different eventual modifiers (the -2 would prevail). Combining Concentrate with M+C maneuvers will still impose the -2 penalty, but you roll against Will-3 after Concentrate maneuvers and against Will-5 after M+Cs. Can anyone think of a reason why some defenses might be difficult or impossible during an M+C, like parries and retreats during a Move and Attack? I can't.

[nik1979]

Originally Posted by Kromm

And to answer the obvious: I'd probably allow All-Out Evaluate to count as a feat of Per and have each second of Evaluate without any defenses give +2 to hit, not just +1, to a maximum of +6. Probably followed by an All-Out Attack at +4, for +10. ;)

Nice, awesome option and one that is realistic given that this level of concentration is the ideal when knowledge of the sequence of opportunity vs constant and continuous risk of danger.

[Dustin]

Move and Ready could be handy - normal move and, on a 9 or less, you can also perform a Ready. Otherwise, similar restrictions as Move and Attack (-2 to balance rolls, no Retreat, no Parries using the Readying hands).

[munin]

Kromm describes some Move and Ready options here, including an All-Out Ready.