I will attempt to explain anecdotally on how to maximize your defender medal gains.
How to Earn 450 Defender Medals from Daily Quests Every Day
First off I should explain what happens regarding daily quests.
In one of the recent updates for dd2, a bug was quietly introduced. it made daily quests erratic by rerolling these quests and making completing them difficult and unreliable.
Also, when you're attempting to recreate my success, there are some things to keep in mind while following this guide: certain 'actions' may cause daily quests to stop rerolling randomly and you will not see the results I claim will work.
These actions may include things like: Swapping heroes while in town/tavern. Buying anything from any vendor, like blacksmith or relic hunter. and even player shops.
In short, just stay as the hero you're currently playing as and don't spend any gold or medals and gems.
I will supply a series of images that should help illustrate how I always acquire daily quests with 450 defender medal rewards.
In the pic below you see I've just entered the tavern via main menu at the start of launching dd2.
Immediately I open my journal to see what quests i have to start with. you can see its 3 map wins for 300 Dm's. It can be manipulated to have your daily randomly land on a daily that awards 450 medals. Also notice how the weekly is still incomplete, yet the daily quests will change on their own in the following images.
Next i head over to the war table and select a map to play. Any will do, I prefer the Dragonfall Bazarre.
Once the map has loaded I check my journal again to see what daily quest it's randomly rerolled to.
This time it's 2 wins for 225. We can do better than that.
If I see that my daily is not one that awards 450 medals, I head back to town. This will also randomly change the daily.
Same deal as before. Open journal and see what's changed.
Now it's 2 Ravine for 300 Dm's. Head back to war table and pick a map. Again I'll choose Dragonfall Bazarr for simplicity's sake.
I finally got lucky and the daily quest has landed on a 450 reward. Exactly what we're looking for. Now, should you happen to get this scenario, all you need do, is complete the map. This should count as an 'action' as i stated earlier in the guide, and therefore locking the challenge from rerolling further.
After the victory chest has been looted i head back to tavern to select the required region and earn my defender medals.
If you happen to receive a daily with 450 medals while still in town or tavern, then you'll need to lock it by buying something from one of the vendors. The blacksmith or relic hunter will do just fine. Plus you may find an item with a high level mod from their shop.
I hope this helps you all out there. For newbies and veterans alike, this kind of info can be invaluable. Especially since defender medals are more useful than they've ever been.