@serv
FON would be lethal even if you did trade.
It really depends on how many cards are left, how much hp he has left, how many swipes have been played, is swipe the only card... etc..
If you had enough to kill him the next turn without going face with cenarius, then it is clearly a mistake. If you didn't, or even if you did, it is a judgment call based on how many cards he has left to draw from, the amount that make you lose by trading etc.. The answer isn't always clear tbh. There are often valid reasons to go face and valid reasons to trade. If you forced him to trade the bot into the cenarius, for example by bringing his hp low enough, then you made the right choice.
There is also the chance you would have lose to swipe regardless of whether you traded or not, granted you'd have another turn to either prepare or recuperate from it. At the very least, losing to like a 1/10 chance of happening is not worth over thinking. Because in the same scenario, 9/10 other times you'd have won. Granted, if you chance of winning by trading was higher than 9/10, you did make a mistake by choosing the lower chance.