Tactics for the Swamp (Fortress).

1. Over 20 levels, you'll get defense about 10 times.
2. With Coliseums and War Schools, this hero gains attack (I take attack, but you seem to take defense - I can't say which is better).
3. This sword and this ring don't appear that often, besides, you usually find something better (Ogre Club, Rider's Gloves, for example).
4. The skill increases not the defense itself, but reduces the damage received by 15% + 15% * (level * 0.05), with an expert defense skill.