Any ability which has an XP cost for the character using it now has an essence point cost instead.
A character subject to the 20% penalty for uneven multiclassing instead may not reduce her essence total below 400 per level.
Any character can gain essence points. The ceremony to gain these points has verbal and somatic components, and takes an hour or uninterrupted time. It can only be performed if a year has passed or the character has gained a level since the last time she performed this ceremony. The ceremony produces 2,000*level essence points each time she performs it.