0.I can't read tips during loading mission of game because it loads too fast. Consider adding "press any key to continue".
1.Skill for figthers "Ignore frozen enemy", so use of corresponding bonus would allow them to reach enemy base quickly.
2.I noticed that shooters, when there are many of them, tend to overdamage enemies. I.e. when they shoot at the same time they shoot the same target more times than enough to kill it. While other enemies nearby, thanks to their luck, stay alive. Maybe you could fix it (so no enemy would be overdamaged. And consequently, it will lead to enemies receiving more total damage), or make special skill "Coordinated attack" for it.
3.Some missions for guilds are quite fun. Please, consider adding ability to play them again, even without getting reward.
4.Display time left for calling wolf pack leader for help again, rolling stone again, etc.
5.Display time left before a player would be able to call the next wave.
6.Make prices in the shop to adjust automatically (Ideally it will make prices more fair, prevent overreliance on some bonuses, almost non-existent use of other bonuses and motivate player to win missions that are most difficult for him/her). It could work like this: Each time player buys one bonus the price for said bonus goes up . Each time hard battle was won without use of said bonus its price will go down (of course there must be limit, like minimum price equal to 1 crystall. I doubt that you will want zero and negative prices). Of course the trick question is "What to count as hard battle?". Probably you could make your game automatically collect data (personally for each player. So prices in the shop will look differently for each player) about numbers of wins (for each mission type) on maximum level of difficulty. Then the game would mark top five (or maybe other number, like seven or three) missions with the lowest numbers of wins (zero number of wins for fresh missions would be counted too) and tell the player that if s/he will win any of them, then prices for any unused bonuses will go down. If too many missions have equally low win count (Like maybe this specific player have never played any mission on the hardest difficulty), then top five missions are selected randomly among them. Possible pitfalls: If you will consider implementing this mechanism, then please make sure that the game doesn't count missions that are not playable yet on hardest difficulty (either because their levels are not implemented yet or player didn't reach them yet or player have never played on said level even once, so the highest level of difficulty is not avaiable yet).