The box hid. The bomb didn't care.
A box’s whole trick is that it isn’t there until it needs to be, but that trick means nothing to an ability that just detonates the ground. Planted, invisible, already sprung — Ziggs’ bomb blows through all three states the same way, because it was never checking for a box in the first place, just for anything standing in the landing zone. That makes dropping a box to hold a bush or block a path a bad trade in this lane specifically: it’s a stationary target sitting in a radius Ziggs can already reach for free. The one angle that isn’t a straight loss is using the box as literal cover, eating the blast in its place instead of your own — except that only pays off if you’re outside the radius to begin with, and against Ziggs, being close enough to matter usually means being close enough for Arcane Comet to already be lighting you up too. Plan the box around dodging the poke that sets up the bomb, not the bomb itself.