The recruits are led through a series of increasingly dangerous obstacles.

The ace inspector was too dangerous an obstacle, to be allowed to live.

You couldn't do anything from the east - the cliff was a more dangerous obstacle than a minefield.

But given a thousand years' warning, your Federation could become a dangerous obstacle to them.

These quickly set hard and proved quite dangerous obstacles.

Bolan wondered if there would be other, more dangerous obstacles.

They were both making light of it, tiptoeing their way around a dangerous obstacle.

Along the way you need to negotiate platforms, switches and various dangerous obstacles.

I have known that you Swifts would be a dangerous obstacle.

Austin saw them only as dangerous obstacles to be removed or eluded.