Board Thread:Welcome Board/@comment-25396902-20140907214218/@comment-27026537-20140907220332

Terra & Double Mettal gives 100% chance, Otherwise;

//ahem// http://dragoncityguide.net/how-to-breed-Armadillo/?basic=0

As the Back to school event is working for you though, you could just wait till the end of the week/next week to get it, but you should be able to get it long before then through other combinations. Good luck :)