TIP FOR GREE: Double Your profits
A few ideas.
Firstly a new elite boss. A permanent boss similar to epic boss but its The Dark Prince and a lot harder. Instead of crafting a legendary you craft The Dark Princes armour, an epic and once you progress an epic+. This mode should be very hard. Instead of only using your main knight to progress through you should have to use another knight after a few fights. This will be the same craftable each week with differing lesser rewards on the way there. This mode is unlocked at level 100. To get to the very end and get 2 craftable plus (like in eb 60 teirs) you will most likely have to gem. To prevent players from just completing the first tier once a week and then be able to craft a plus from armour fragments the next week, there will be one fragment once you get to the craftable tier. Called Dark Prince kit and Dark Prince kit+. Possibly an extra two tiers after you've got the first kit tier where you get the Dark Price ring the further along the Dark Prince amluet. Maybe legendary.
My next idea. New wars in between the current wars at similar intervals. Fusion jewelry blitz, Rotating between fusion rings and fusion amulets each war. Another Epic War unlocking epic war rings and amulets and for first place plus versions. In this war you are rewarded both the war ring and amulet. Legendary rings or amulets for lesser tiers. Lastly Raid Boss unlocking epic raid rings and amulets and plus for first. As before you get both the ring and amulet with legendary rings for lesser tiers.
Last idea. Make a new building that takes up four spaces (instead of two training grounds like most players have). Possibly a farm. This will generate slightly more than two training grounds and have a huge bank of maybe one hundred thousand. Higher once you upgrade it. Maybe 300 gems to fully upgrade.