Mass Invisibility is the combat version of Improved Invisibility.
|“|| Mass Invisibility|
Upon casting this spell, the wizard causes all friendly creatures within the area of effect to be affected by the spell Improved Invisibility. This spell is similar to Invisibility 10' Radius, but the recipients are able to attack, either by missile discharge, melee combat, or spellcasting. Note, however, that there are sometimes telltale traces, a shimmering, so that an observant opponent can attack the invisible spell recipient. These traces are only noticeable when specifically looked for (after the invisible character has made his presence known). Attacks against the invisible character suffer a -4 penalty to attack rolls, and the invisible character's Saving Throws are made with a +4 bonus.