Also, you should be able to clear the surrounding area before entering the tent, which will leave you with only a couple to deal with inside. Fights outside can attract nearby orcs, but not as many as the orc chief calling for help, and there is plenty of room outside to withdraw a bit (so they can not surround you and the ensuing fight has less of a chance of attracting more orcs).
Level 4 or 5 of Hell Spikes is very effective for crowd control (it does physical damage, so can not be resisted) and against a couple opponents you can cast Blind on them first, so they can not attack you.
Burning Wall is good against groups. You can either cast it as you are strategically retreating, or get your opponents in a tight group and run around them.
