Hamas made a dead set against the enemy.
Here, 'dead set against' means-

• Hamas made a dead set against the enemy.
- Here, 'dead set against' means- খ) firmly determined

• dead set against (doing) something
- English Meaning: firmly determined; to be completely opposed to something.
- Bangla Meaning: দৃঢ়প্রতিজ্ঞ/অটল; সম্পূর্ণভাবে বিরোধিতা করা।

• Ex. Sentence: Hamas made a dead set against the enemy.
- Bangla Meaning: হামাস শত্রুর বিরুদ্ধে দৃঢ় প্রতিজ্ঞাবদ্ধ হয়েছিল।

Source:
1. Cambridge Dictionary.
2. Merriam-Webster Dictionary.