"We'll have about twenty seconds." If she and the dwarf both understood their mimed conversation on the subject correctly. And if the fuses on these devices are consistently predictable. Dwarves are generally good at this sort of thing, but neither these explosives nor these dwarves are anything they've seen before.

Just in case, "We should plan to be a safe distance in ten if we can. Fifteen at the most." Which may mean swinging out of range rather than climbing up, depending what the terrain below them looks like.

"May I borrow a glove? For the rope."