Perhaps unbeatably would work better. It carries more validity as a word, and in a sentence with several long words it is less of a mouthful.

Or another possibility might be invincibly. That's a word alright.

Perhaps unbeatably would work better. It carries more validity as a word, and in a sentence with several long words it is less of a mouthful.

Or another possibility might be invincibly. That's a word alright.

Others: - indomitably, unassailably