Level Adjustment

Level Adjustment is a games mechanic native to Dungeons & Dragons 3rd edition, which has yet to resurface. In essence, because different possible PC races have different levels of strength, Level Adjustment was brought in as an attempt to provide some form of balance; races with particularly strong benefits, such as Planetouched counting as "Native Outsiders" and so being resistant/immune to various common spells, would be treated as if they were a certain number of levels already before they could calculate their levels. In essence, actually taking levels in a class was treated as multiclassing.

A good idea, in theory. In practice, most found Level Adjustment didn't work out, mostly because of the fact it combined problems already present in multiclassing with the fact that, in essence, you were ahead of the rest of the party early in the game, only to then struggle to catch up with them as they had less of an XP tax than you did.