After Thaviks disappear and goes invisible after taking damage, it is possible to see him climbing the walls on the arena. If you shoot him, he will fall off and instantly die, ending the strike
Video proof: https://youtu.be/eCRjzlDBuCY
I assume this is a cheese.
[spoiler]Video not mine[/spoiler]
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Finished the nightfall, didn't see him on the wall. I don't know of we just missed him, or if it doesn't work on the nightfall. There is a conflux that respawns, allowing the timer to get maxed out at 13 min. We finished with 38 seconds left. Not an enjoyable NF.