hmm...this is what i do if i want to kill someone who has low
maximum hp (eg. TB, enchantress, naix, sniper, zeus).
go from any direction (front, side, back. but you must have good
timing and aim), cast light strike, dragon slave, then
laguna.
the reason why I cast light strike first, is because it's very hard
to hit a target moving AWAY from you with it. it also lowers the
chance of them escaping due to the 1.6s stun, which is crucial to
slayer, as she can't chase the enemy for nuts.