Short and to the point.

If you have the Underworld DLC, go to the campfire @ 623, 215 on the underworld map and equip the animal food. Then go to co-ordinates 614, 181. here you will find an adult deer and 2 fawns, drop some food near them and wait till they eat, it might take a second of two before they do.

Once all three are befriended return to the campfire, sit at the campfire and the deer will return to their spawn area and your food will be replenished, rinse and repeat feeding the same 3 deer until you have fed 10 deer in total and the achievement pops.

I hope you found this guide of help, all comments, suggestions and criticism (constructive) is gratefully received.

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