Yeah given what happened during that i'll definetly asking to see the rules for shit like this in future because i didn't really contest anything much, mainly because i don't know all the rules for warhammer as well, still getting back into the swing of all the different rules. Like i had the guy i fought the Genestealer cult remove models that were "closest to the firing unit" when i used blast markers on some of his units when they weren't even under the marker, i did think that was wrong and its under the blast marker only and tried to argue that but ended up just accepting it, though i looked it up after and turns out i was right.
That's actually correct. In the rules for Blast, you'll find: "Remember that any Wounds inflicted by weapons with the Blast special rule must be allocated to the closest model in the target unit even if it is out of sight of any models of the attacking unit."
Though if it's also a Barrage weapon, the shots instead come from the center of the blast marker rather than the direction of the firing unit.
Ask not the Eldar a question, for they will give you three answers; all of which are true and horrifying to know.