Text: But he knew well that he was under an attack delivered with a purpose, and with all the dirty tricks of a no-rules, back-alley fighter.
Entailment: He knew that he was versus the dirty tricks of a no-rules, back-alley fighter, and that the attack was delivered with a purpose.
Contradiction: But, he was aware that the attack was random, and he was fighting some random person on a martial arts tournament.