Raditz uses the bottom 3 cards of the discard deck for the next combat instead of the cards from his life deck. If there are not enough cards, don't use this ability. Discard from the game after use.
I can tell you're not from this planet.
Errata:
Treat this card as if it read, “Use when entering Combat as the defender. Instead of drawing 3 cards from your life deck, draw the bottom 3 cards from your discard pile. Remove from the game after use.”