What I am having a problem with is getting the third snake to the bomb.
I take it that the first two where easy because you were leading the serpents from in front. However, you can also maneuver serpents from behind in the same way... a serpent that's moving directly away from you will keep doing so until it runs into something. So the "
trick"
is to get the serpent to be moving north directly towards the slot when you're directly south of the serpent. Fortunately, the target direction is north which makes this relatively easy (because snakes have a preference for north and east when they don't have a better choice).
The trick I use for that is
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×to get the serpent moving horizontally between me and the target, while standing directly south of the target. When the serpent is directly in between, I move horizontally in the direction opposite of the serpent's movement (so the serpent finds me suddenly behind it's movement path). The serpent will then turn to it's default (north) providing that that's not blocked (else it will continue to try east, then south, and then west). Once it does that, immediately move back in line to keep the serpent heading in the correct direction.