warning... this achievement can be glitchy 4 some..the glitch seems to come from people who play 2 play throughs.. here are some solutions from other sites to help so u hopefully wont have this problem...
1 if playing through for the first time turn auto save off
2 play through the game on hard without turning your console off or reloading a save should only take 3 -- 6 hours.. again with auto save turned off
3 if u have beaten the game on hard with auto save on and still no achieve.. after u are done turn auto save off..worked for some, just not 4 me :(
4 as a last resort go into dashboard and delete all save files and go through again with auto save off.. step 4 worked 4 me as a last resort
if i have missed something or u personally know a better way leave a comment so i can update the solution...
i would write an actual guide to go along with this solution but truly their is no need only hard part were the duals and 4 those just use the shield spell and hope ur allies kick some ass.. just be warned if u are only playing this game on hard the mini games are far harder than they would be on easy... may want to play thru twice 4 that reason alone