Note that if your emissary doesn't have hand slots, they can avoid the negatives of receiving the trident while still competing for the bonus experience. The Ophanim angels of Ashdod, for instance, are great for this (if a bit advanced.)
Another strategy is the kamikaze combatant. They probably won't win, but they might take out another player's hero (e.g. load up with medallions of vengeance, cursed items, disease causing ability, etc.) This is probably only feasible in the early game, as if anyone sends in combatants later on, they'll be high-end thug or SC caliber. Still pretty much a gamble.
Note that due to lack of participation, it can sometimes be worth sending in a mediocre combatant that would greatly benefit from increased experience; if the risk of losing them is not too great, the potential reward might be worth it. Who knows; you might win by default
