Surface stratum zero

Surface stratum zero is one of the upper levels of Iacon.

Regeneration One
Apparently betrayed by their leader Grimlock, the Dinobots Sludge, Snarl and Swoop found themselves pursued by a team of Decepticons and Autobots corrupted by Scorponok's Gene Key led by Highbrow across surface stratum zero. Aware that they were somewhat exposed, the Dinobots turned and headed into the under-city before Swoop realised that the best way to bring Grimlock to them would be to attack The Nursery instead.