Dungeons & Dragons: Chronicles of Mystara

You need to open, unlock, or break open 50 chests to finish tier 3. There are plenty of chests in the game and you will naturally get most of them on the first play through of each game. You can finish off the remaining chests while working on cleaning up challenges for the Completionist achievement.

For those in need of extra chests or if you just want to grind it out here is the best method!

Using the Dwarf (you need him to open chests twice) start off on chapter 1 of Shadow Over Mystara: Descent from the Broken Lands. You will always get 1 or 2 chests right off the bat when moving towards the right. Kill all the enemes and when you enter chapter 2 - Village of Trintan move your character towards the top of the screen slight after the first rooftop closest to top.

You will enter into a secret room with 4 chests! The chest closest to the back will always contain a weapon to equip and a piece of armor! So you can also work towards your Weapon Equips and Full Metal Jacket challenge respectively! You don't have to start on Ch 1. but it does give you 2 extra chests so I always did (also so I could work a few toward my kills!) just for a few kills and the extra chests!

For it to count you must DIE and the let the time RUN OUT! I could not just quit to the menu and have it count but it is a pretty quick process.