5e Monster Design: Hobgoblin

[mflayermonk]

So I have been having some trouble understanding how to properly rank CR for the Hobgoblin, which has an AC of 18 from its armor. This is a CR 13 in the DMG table pg. 274.

I need help with how to effectively design monsters with armor. How much should chain + shield add to a monster's CR?

Any help or tips is appreciated.

 

[Bupp]

Using the chart to assign CR to a creature you start with it's hit points, then adjust for AC and damage output. The hobgoblin's 11 HP place it in the CR 1/8 line. Then you adjust for AC. A CR 1/8 creature should have an ac of 13. For every 2 points of AC, you raise the CR one spot, which gets you to the CR 1/2.

Actually you should move 2.5 spots on the CR chart, but the hobgoblin's average damage is low for a CR1/2 creature, so I think it averages out.