Check the table below to find out about the intelligent opponents you may encounter during your journeys. Naturally the chart doesn't list any bosses, because you'll fight them only once and the main section of this guide describes how to kill them.
Threat level: 3/10 - 6/10
In most cases enemy archers won't be a big problem and they won't endanger safety of your team, however later in the game (especially while completing Denerim's final quests) you may encounter their elite versions. Their attacks will inflict more injuries or even immobilize your teammates for a few seconds, so as a result you will have to focus on killing them quickly.
Threat level: 5/10 - 7/10
It's always a good thing to start each battle by eliminating hostile mages. This will prevent them from aiding other opponents or injuring your teammates with offensive spells. Use your warriors to get to the mages quickly, but watch out for glyphs that may be found nearby.
Threat level: 6/10 - 7/10
They're the special kind of mages and you'll have to pay even more attention to killing them as soon as possible. Thankfully blood mages often work alone, so you won't have to worry about attacking other enemies at the same time. You can meet some of them in the abandoned building in Denerim, in The Circle tower or in eastern Brecilian forest.
Threat level: 4/10 - 5/10
You'll be dealing with three types of opponents here - mercenaries, assassins and rogues. Most of them will act like shrieks and attack the team using camouflage. Pause the game as soon as they've revealed their positions and plan your strategy to offer maximum protection to your mages and archers.
Threat level: 6/10
You won't encountered qunari mercenaries too often and it's not a coincidence, because killing them won't be easy. Expect huge health drops while dealing with them in close combat, not only because of their unique skills but also as a result of them using powerful melee weapons.
Threat level: 2/10 - 5/10
There are three major types of enemy warriors - soldiers, knights and templars. Naturally, members of this class will take part in almost every large battle and in most cases defeating them won't be a big problem. You should only watch out for elite dwarven warriors and for templars (encountered mostly in The Circle tower).