Splice is a keyword mechanic found primarily on Clarity cards, but also occurs on neutral cards. Splice reads, “When you select this, you may splice it.” Splice is a mechanic that is watching for a card that you play from your hand or a card you already have in play to selects this card. When that happens, the Splice ability occurs.
For example, the card Favored Subject says, “Splice: You gain 3 [PRE]. (When you select this, you may splice it.)” If you play a card from your hand that selects Favored Subject, in addition to whatever the card does, Favored Subject adds, “You gain 3 [PRE]”. If you are able to select your Favored Subject several times in a turn, it will trigger for each selection made.
Splice does not trigger when an opponent selects your Splice characters.