I don't have the spell description at the moment but IIRC it's like you said - it's not an area spell, but rather a targeted spell (with multiple targets), you get to choose the targets, and there is no chance of hitting allies by accident.<br/><br/>So you get target anything which is<br/><br/>1. In range 0 sometimes these spells have both a limitation on range from your character, and distance between any two targets, like Slow http://www.d20srd.org/srd/spells/slow.htm (http://www.d20srd.org/srd/spells/slow.htm). I forget whether Mass Whelm has such a restriction.<br/><br/>2. In line of sight/effect (i.e. you can see them; they aren't invisible, behind a wall, or across certain special line-of-effect-breaking barriers like Wall of Force.).<br/><br/>3. Doesn't exceed the maximum # of targets for the spell.<br/><br/>Generally speaking, if the spell entry has an Area: line, it works like fireball, if it has a Targets: line, it works like slow. Spells that affect every creature in the area, like fireball, will usually also say something in the description like " to every creature within the area." Another rune of thumb - not an actual rule that I know of, just a 'pattern' - is that if the spell has any limit on the number of targets (besides an implicit limit to how many could squeeze into an area) you can almost certainly choose them (within the spell's limitations) and don't have to choose any you don't want to. Offhand I can't think of any spells that act on targets 'in order' based on proximity to you (although some spell effects are always centered on you) or require that target selection be done in that way.<br/><br/>A third type of spell is that which involves an attack roll - usually  touch, ranged touch, or ray. These are sort of like attacking with a weapon; you make an attack roll that has to hit the target's touch AC, and is subject to miss chances from effects like Blur and Toria's 'haste-blur' thing. Things like the +1 attack bonus from Haste would apply to these attack rolls.<br/><br/>Non-attack-roll "Targeted" spells like Slow or Hold Person are not subject to miss chances (but if the foe has total concealment, such as from Invisibility which you can't see through, you can't target it at all; you don't have 'line of sight').