Making Inventory Space
During 10 day raid events, a very popular technique is to go easy on boss engagements and hold onto as many specials as possible until day 6. The reason troops do this is because after day 5, the boss has the chance to be enraged, giving double trophies and each time the boss is engaged it will cost more special donations. There are a few things you can do to make room in your inventory to prepare your troop and a few tips are listed below.
Simply leveling up and monsters will clear out some space. A feeding booster is the best way to do it because of the double XP when feeding. Max any monsters that you use!
Evolutions are particularly great for making room in your inventory. Not only do you do a lot of feeding to max all the mobs, the 4 specials and the feeder monster clears up 5 precious inventory spots. See the Evolution page for more details.
Simply selling mobs to increase stones is a simple way to do it. Selling puzzle pieces is the only way to get rid of them, so if you've had 1/6 of that monster for months, sell it! There are 2 ways to sell monsters. The first way is individually by selecting the monster you want to sell. The second is in bulk, where you select the monsters you want to sell in your main inventory window.
Selling in bulk
Leveling up passives is just good for your team in general. You may have trouble letting go of a monster of a certain rarity, but just think about how much better your team will be. R-Boosting by feeding event reward mobs and treats is another great way to enhance your team.
Salvaging enough mobs will get you an egg cooking for a rarity above.
Donating Specials to the Troop Pet
Troop pets are always hungry. As of right now, they can only be fed Floralbonitas, Glohawks, and Brainfreezes. Get your pet leveled up for troop wars and better gifts from petting.
Setting an Arena Team
If you don't have a team in the arena, you can open up 5 spaces by just tossing whatever mobs in there.
Buy Storage Boxes
Probably the most obvious way to open up inventory, but 150g is a steep price. If you don't spend and you really want to buy one, be sure to do some Tapjoy deals!