I like the cage nerf, but perhaps gnomes can make a different "cage" or you can feed a dragon 10 people in a row it becomes full and tired and you can tame it then.. lol
No, 10 gnomes won't be enough. A dragon is 1666 times bigger than a gnome.
But it is a good strategy. If one or two of the 10 gnomes can survive the dragon breath, they can drill rooms in the dragon's teeth, and live there. Then we say we have tamed the dragon.
Don't the gnomes have a web launching weapon? Webs temporarily remove Trap-Avoidance, so you can handle stuff like this by having a web-launcher squad for backup.
Gnomes have many ways to web creatures, glue grenade, frost caster, web turret, and a lot of other stuff to stun enemy.