Roy's prediction was right. He could indeed withstand the explosive power of this small-yield tactical nuclear bomb.
Compared to other elemental magic, the ice element could form a substantial physical defensive structure to resist the blast wave. At the same time, because of the low temperature of the ice element, it could also resist the high temperatures produced during the explosion. This was an advantage that other elemental magic could not match.
As for the most fatal radiation of the nuclear bomb, Roy's Desolate Virus absorbed it during the explosion. And after absorbing the radiation, Roy could clearly feel that the Desolate Virus had become stronger!
In other words, when using these tactical nuclear bombs to deal with enemies, not only could they cause immense damage, but they could also strengthen Roy.