Having trouble with turn based combat system?

Im making a card/magic game that is turned based where you can have up to 4 people and 4 enemies fighting against each other. So far im separating the battles to invisible platforms throughout the map when you initiate battles to npcs in the game. My biggest problem is when its the players turn to choose a card and which enemy to use it on, im having difficulty figuring out how to send both sets of information(the card, which is chosen in the gui, and which chosen enemy) to a script in the serverscriptservice.

the way the turn system works is one person can initiate a battle with a npc and other people can join the battle later. on the players turn, players have 20 seconds to choose their card to use and who they use it on, the enemy(if its a damage card) or even another player(if the card heals.)