Top Level Enchantments - Leaving aside the Healing Aura ones, top level enchantments require Malachite Gems to use. But the benefit you get for that is pitiful. Malachite Gems are extremely rare, you're unlikely to see more than 14 in a game, but the Level 10 enchantments aren't noticeably better than a level 9 enchantment. There are a few possible fixes for this:
1) Make the Level 10 enchantments a LOT better. When I can get a +24 Melee Damage enchantment for basically nothing, there's no reason to waste a gem to go to +27. But if instead, the Level 10 was +39, 15 points higher, that might be something to think about. THe higher the boost, the more tempting the enchantment is.
2) Have your runners be able to search for Malachite Gems. The problem with this is that it still theoretically makes this rare commodity an infinite supply, but it can be balanced out a bit if you make the searching more difficult and less worthwhile by using any of these:
a) Increase the amount of time the runner is away - instead of coming back on your next return to the tower, they come back on your third visit to the tower. Gems are rare, so taking longer to search is reasonable.
b) Increase the chances of injury when searching for Malachite Gems. The longer you're in the field, the higher the chances of injury.
c) Only one Malachite Gem can be found per run. This should keep them valuable.
d) There's only a 5% chance that you'll find a gem on a run. So, for every 20 times you send a runner out (and they return uninjured), you might find one Malachite gem.
That should keep Malachite Gems hard to find. But please also make the enchantments more useful.
