It may seem intimidating and strong, but it is not at all hard to defeat. If you are a melee/physical fighter (warrior, ranger) you will miss most attacks due to Blurred Vision, but that's an acceptable loss as you have a high armor level to endure its attacks. Alternatively you may switch to a wand or a staff and the River Drake will never cast Blurred Vision on you unless you switch back to a martial weapon.
If you rely on spells to deal damage you can kill it rather easily. Just be sure to be wary of your lower armor level.
- The river drake does not appear if there is someone in your party who had not completed the <primary profession> Test when you entered Lakeside County.