User blog comment:B214/Volume 22 spoilers/@comment-180.254.53.9-20160719190550/@comment-9595671-20160722203343

Unless Trihexa were to be weakened that is, we all saw Ophis of all beings have most of her power siphoned away from her, so it's not outright impossible.

The problem is how Trihexa can be destroyed without a method that would render it's death moot, like Shiva implied and what may be a fight with him and Great Red. (can't remember if this includes Ophis fighting with him or not)

The closest thing I've seen that could weaken or possibly kill Trihexa is Samael's poison because Trihexa's appearance does mention some Dragon traits, meaning the poison should be as deadly to him as it would be for Ophis and Great Red.