SRD:Level Adjustment (Creature Statistic)
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This line is included in the entries of creatures suitable for use as player characters or as cohorts (usually creatures with Intelligence scores of at least 3 and possessing opposable thumbs). Add this number to the creature’s total Hit Dice, including class levels, to get the creature’s effective character level (ECL). A character’s ECL affects the experience the character earns, the amount of experience the character must have before gaining a new level, and the character’s starting equipment.