Totally legit but ... Idk... Dirty perhaps?

(placed flair as Social Interaction since this is an experience I saw on a gaming table and wanted to share the story.)

I was sitting at a table browsing another guy's binder in view of another table, so my attention wasn't fully on their game. But on this turn I paid attention to their banter. The turn in question has three players in play, A, B, and C, and it's Player A's.

Player A had not been able to do much in the game and his commander keeps getting removed. During his turn, he says he got an opportunity to turn the game in his favor but only if he can play his commander again but even with all his treasure tokens and untapped lands he lacked 1 mana to do it (he was vocal about this, even counting his resources). Player B has a [[Spectral Searchlight]] and offered to use it to give Player A one mana of his choice, Player A happily agrees and says he will focus on Player C. Player C is quiet but nervous, he just nods and says "okay."

Player B taps the searchlight and Player A sacrifices the treasure tokens, taps land, and casts his commander. Player B uses [[Quench]] to counter Player A's commander. Player A was confused. Player C was confused. I and the binder guy were confused. Player A was lost for words but shook his head and scooped stating "good game, thanks." He left the table. Player B then shrugged and took his turn. Player B and C got a few more turns before the game ended. I didn't see the end though since binder guy and me walked away to another table to look at other people's binders.

It is a legit play... I know, but man that is cold-blooded. I just had to share this.