He nods, knowing that they both are aware of the specifics of the plan. He grabs the knotted end of the cord in his jaws and pulls it taut as Sun-Cursed bites onto the portion near the end. With a heave they pull in unison, the slab barely lifting as dust and dirt come off of it when it slides back onto the floor. This is going to require much more effort than he anticipated.
"This slab is a lot heavier than I thought it was, so once you let go and run in, there is a chance that I won't be able to follow you. If that happens, I want you to keep going. We need to get the Orb no matter the cost." With a nod of understanding shared between them, he once again grabs hold of the cord and uses his entire body to pull. Knowing how heavy the slab is with their first attempt, he is prepared for the strain he must exert in order to lift it high enough for Sun-Cursed to run in. To her credit, Sun-Cursed was putting up a valiant effort in pulling as well.
When the slab is high enough, their eyes meet. The signal. Sun-Cursed lets go of her part of the cord and makes a mad dash through the opening. Smoldering Ember has to hold all the weight of the slab on his own long enough for her to pass through. If his hold fails, it could be fatal for her.
With formidable effort that he feels like he's already put in once before, he holds the cord down as Sun-Cursed makes it past. They share another look between each other, each one at opposite ends of the threshold. The plan only went this far. They never talked about how he was getting through. What now?
Smoldering Ember lifts his forelegs and hooks a portion of the cord to his left, then he does so again and hook the cord to his right, each time the cord getting shorter and his distance to the stone slab shortening. After doing this a few more times in quick succession, he kicks back hard with his hind legs and tucks into a roll, propelling his balled up body forward as the tension on the cord relaxes and the slab comes hurtling back down towards the floor.
BOOM!
As the shaking and the cloud of dust subsides, Sun-Cursed sees the form of Smoldering Ember splayed on the floor just a bit past her. Breathing heavily and more than a little dirty from his rolling maneuver, by some miracle he made it into the next chamber!