any guide or suggestions on what cards is best to this class ?
That is a very weird build that you have. The linker and the Sheriff are both boss-killing classes (PVE). The cards will depend if you want a Build AA or a Build Burst. It will also depend if you want to focus on the PVE or PVP. By the way, the Sheriff has potential for PVP.
I’m SR>Enchanter>Sherrif. My Build AA.
Here are my suggestions for the cards:
Unicorn - Increases damage against Dark property monsters by [Star]%
Deadborn - Physical Critical Attack +[Star*20]
Centaurus - AOE Attack ratio +[Star/5]
Nuaele - Magic Defense +[Star]%
Armaos - 10% chance of generating [Star*100] Shield for 10 sec when attacked
Zaura - Physical Defense +[Star]%
Marnox - Critical Rate +[Star*15]
Ellaganos - DEX +[Star] - AA Build
Blut - CON +[Star]
Mummyghast - STR +[Star/2], DEX +[Star/2]
Netherbovine - STR + [Star] - Burst/AA Build.