# How do you figure the blast radius of an effect in Mutants & Masterminds?

Grenades and other explosive powers have the Area modifier applied to them. When determining the range do you use the distance column or the volume column in the ranks and measures table?

• Is there anything I can add to my answer to make it more suitable to you? – Sean Duggan Apr 8 '16 at 20:36

The metric is Distance for 5 of the effects as per the Area modifier description. Shapeable is the outlier, being based on Volume rank (although there are a fair number of people who feel that it's either not useful enough or too useful depending on your interpretation of 30 cubic feet of volume and how much of it has to intersect targets). And, of course, Perception is based on who can perceive you, so there is no strict rank.

Burst: The effect fills a sphere with a 30-foot radius (distance rank 0). Bursts on level surfaces (like the ground) create hemispheres 30 feet in radius and height.

Cloud: The effect fills a sphere with a 15-foot radius (distance rank –1) that lingers in that area for one round after its duration expires (affecting any targets in the area normally during the additional round). Clouds on level surfaces (like the ground) create hemispheres 15 feet in radius and height.

Cone: The effect fills a cone with a length, width, and height of 60 feet (distance rank 1), spreading out from the effect’s starting point. Cones on a level surface halve their final height.

Cylinder: The effect fills a cylinder 30 feet in radius and height (distance rank 0).

Line: The effect fills a path 5 feet wide and 30 feet long (distance rank 0) in a straight line.

Perception: The effect works on anyone able to perceive the target point with a particular sense, chosen when you apply this extra, like a Sense-Dependent effect (see the Sense-Dependent modifier). Targets get a Dodge resistance check, as usual, but if the check is successful suffer no effect (rather than half). Concealment that prevents a target from perceiving the effect also blocks it. This modifier includes the Sense-Dependent flaw (see Flaws) so it cannot be applied again. If it is applied to an already Sense-Dependent effect, it costs 2 points per rank rather than 1.

Shapeable: The effect fills a volume of 30 cubic feet (volume rank 5), and you may shape the volume as you wish, so long as it all remains contiguous.

Each +1 point increase in cost per rank moves the area’s distance rank up by 1. So a Burst Area with +2 cost per rank has a 60-foot radius (distance rank 1), a 120-foot radius at +3 cost per rank (distance rank 2), and so forth.

• Can this create bursts with areas of less than rank 0 burst-- For instance, a 15-ft area? What would the effective point cost be, if so? – LeesusFreak Jan 19 '16 at 16:09
• @LeesusFreak My impulse, based on 2E M&M which had feats to increase and decrease area, is that you'd charge for an Extra to let them decrease the effective blast radius too. Being able to shrink your last to a smaller area, particularly if you can control it more finely, allows you to "target" your area to avoid innocents and/or collateral damage. Shorter answer, the rules don't cover it, so you talk with your GM. – Sean Duggan Jan 19 '16 at 16:13
• Yeah, it seems like adding the Selective mod is a much easier way to just ignore larger areas, but isn't mechanically 'pure'... – LeesusFreak Jan 19 '16 at 16:16