I saw the MCD-6922 which was marked as works as intended. It's a bug actually. Normally the highest power can be gained from the tower is 263. But during this bug a equipment whose power even higher than 300 can be gained. The possible reason may be that after finishing a level, it will record all the stats except the current floor, which makes it possible to kill the boss once and once again to gain a equipment with a extremely high power.

To reproduce:
1. Go to the tower in apocalypse difficulty.
2. Pass the floor 1-8 as usual.
3. When finished floor 8, use the stone totem to back to the camp instead of go to the next floor.
4. Back to the tower and continue passing the floor 8-10 as usual.
5. After finishing floor 10, go to the next floor, and then press Alt+F4 to shut down the game right away.
6. Restart the game and go to the tower, you can see the current floor is 8, but bosses defeated count has increased once(as shown in picture).
7. Repeat step 4-6 as many time as you want.
8. After kill the boss for a suitable count, be killed by mobs to failed the challenge. Then a equipment of extremely high power can be gained(as shown in picture).