Rule · Chapter 6
cr:6.4.7
A self-replacement effect is a replacement effect that applies to a preceding effect generated by either the same ability or a leading connected ability.[1.7.6] A self-replacement effect is typically written in the format “[EFFECT]. [CONDITION], instead [MODIFICATION],” where EFFECT (if any) is the preceding effect the replacement applies to, CONDITION specifies the replacement condition, and MODIFICATION specifies the partial or full replacement of the event created by the preceding effect.
Example: Tome of Divinity has the text “Draw 2 cards. If a card has been put into your soul this turn, instead draw 3 cards.” This is a discrete effect and self-replacement effect. When the card resolves on the stack, if the player has put a card into their hero’s soul this turn, the self-replacement effect replaces the event of drawing 2 cards with drawing 3 cards.