Pay
To pay (
"Spell Economics" allows the player to activate Spell Cards that normally require Life Points to be paid as a cost, such as "Dimension Fusion" and "Brain Control", without paying those Life Points.
Paying Life Points is distinct from taking damage. Whereas if a player takes damage that reduces their Life Points to 0 they lose the duel, if a paying Life Points for a cost would reduce their Life Points to 0, they instead cannot perform the action that requires that cost.
If a player cannot or does not pay for the Maintenance Cost of a card, such as "Terrorking Archfiend", then that card is destroyed (but not by a card effect); if a card forces the opponent to also pay a maintenance cost, such as "Battle-Scarred", if the opponent cannot pay the Maintenance Cost and the controller of the target can, the opponent's Life Points remain unchanged, but the controller has to pay and it is not destroyed.