if it splits, all arrows can seek, however only 1 will re-seek the original target. in other words, i don't think more than 1 of the split arrows can hit the split-originating target again. i have not tried it in a large group so i am not sure if the split arrows can be split. going to try and test that now.
edit: more testing. it seems like there is a "no track" distance that the 3 arrows will travel before they seek. if one arrow hits during this period, another may track back to that same target. I have not yet seen 2 arrows track to the same target. i have not yet seen a second split.
if it splits, all arrows can seek, however only 1 will re-seek the original target. in other words, i don't think more than 1 of the split arrows can hit the split-originating target again. i have not tried it in a large group so i am not sure if the split arrows can be split. going to try and test that now.
edit: more testing. it seems like there is a "no track" distance that the 3 arrows will travel before they seek. if one arrow hits during this period, another may track back to that same target. I have not yet seen 2 arrows track to the same target. i have not yet seen a second split.
there we go.
Also, i think the formula for Devouring may not be correct, the damage increase only occurs after a split, so i think it should be .35^n-1 x .7^n
(its been a while since i've taken a math class)