Text: You might end up with such a brave battalion of heroes that when a grenade lands in their midst, there is a competition to see who gets to jump on it to save the others.
Entailment: A competition to see who gets to jump on the grenade to save the others--this is the kind of behavior you can expect from the brave battalion of heroes that you might end up with.
Contradiction: You can't possibly expect to end up with a brave battalion of heroes with that attitude.