Okay, now I'm motivated enough to get back to this. I'm gonna attempt to explain this as comprehensively as possible.
Dagruel realizes he needs to eliminate all of Veldora's clones as he will keep shifting his existence, and is fully intent on doing so:
ÒÇîWhat no chance to win you said? What a nonsense you talked about…… But it seems to be true that you're different from the old time. If I can't see where your main body are, then I shall erase all of your clones at the same time!ÒÇì
"Also, all of Veldora's clones, in order to eliminated them together at the same time."
However, not only does Veldora survive, but his clones:
"For Dagruel to be surprised was normal. In the isolated space, there was no escape. Yet, for Veldora to survive after receiving the direct hit should be impossible. But, it's a fact that Veldora survived."
But, he's heavily damaged:
"His wings were tattered, and his whole body was injured all over. He just pretended to be okay. In fact, he was not completely evading the attack just now."
It's revealed he used Probability Manipulation to survive, but some of his clones were destroyed:
"Making good use of Ultimate Skill『Chaotic Lord Nyarlathotep』, Veldora thinned his existence probability to the utmost limit, and was barely able to evade the interference wave of the destructive energy. However, several of the clones failed in evasion, they were all annihilated."
If Veldora messed this up even a little, he would've been destroyed (even though he would've regenerated via Rimuru). Keep in mind, he barely escaped:
"It's a terrifying technique, and if Veldora was even a bit late, Veldora would be definitely destroyed."
At the end, it's shown that some of his clones DID survive, whilst others died:
"Veldora integrated all of his remaining clones and checked the current situation."
