Optimal Medallion Upgrade Path?

The last time I played Digfender I hit a wall partway through and was pretty much unable to make any more progress. I'm guessing it has to do with how I chose to spend my upgrade points on the medallion tree because these upgrades have sweeping affects across all towers, enemies, etc.

You can undo and respec upgrade points at any time, but I'm not the best at comparing benefits and choosing the right ones, hence my frustration.

What should I be focusing on so I don't get stuck again on this playthrough?

Solution 1:

I think the answer depends on what type of enemy is giving you trouble since each tower type is good for different things.

Personally I focus my upgrades in the fire tree (particularly damage, range and cost) since fire towers are good against everything except armored enemies. If I get stuck on a level with armored enemies, I reset and switch to lightning since lightning attacks ignore armor.

For the skull upgrades I focus on anything that helps get more resources or improves support towers.