New explosive arrow and who gets credit for BOOM

Ok, the new Explosive Arrow now works like Halos Needler, so adding arrows increases the AOE like before BUT they are now all set off in ONE big boom. I like this, but have questions of who gets credit for the big boom at the end.

Lets say you're running leech and have Explosive Arrow Ballistas (ie the Ballistas are using Explosive Arrow). You fire a Explosive Arrow into a foe, your totem then does too. The boom happens. Do you get leech stacks off it? Ie is it YOUR boom because you fired an arrow and contributed to the boom, or is it your totems boom because it hit last? Do you split the difference?

I'm wondering from a technical standpoint, so opinions are nice, but looking more for hard facts of "yes, it does x because blah blah" or "no, it does y because blah blah". Thanks.

p.s. also wondering same for traps and mines adding Explosive Arrows to foes you have tagged with Explosive Arrow, but care much less.

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The explosion consumes all explosive arrows on the target and deals the combined damage of all arrow explosions, letting you build up a very strong Ignite, and the skill deals more damage with Ignite for each explosive arrow in the target.

You'll get leech on exactly the damage done by your arrows exploding.

The only thing I don't know is who gets credit for the kill (for "on kill" effects). Presumably the arrows will deal damage according to the order in which they were applied to the target, so the particular part of the explosion that deals the kill will grant the on-kill effect...? But the boom in total "belongs" to everyone who contributed to the explosion, shared according to the damage dealt.