Fuse

Fuse is a keyword featured on split cards from Dragon's Maze.

Any time you could cast a split card with fuse, you can choose one half and cast it, just like any other split card. If you're casting it from your hand, you have the additional option to cast both halves as a single spell by paying their combined cost. Instructions on the left half are processed first, then the instructions on the right, and targets for the two halves are chosen separately.