How do I get into the Inverse Castle?

Solution 1:

Skeleton Ape barrels can destroy wooden planks.

The wooden floor isn't an exit, but an entrance into a new area. Lure the DK impostor close to it and let it release its barrel.

It'll lead to Abandoned Mine and Catacombs, each with a boss. The rest should be straightforward as long as you have the Echo of Bat you get for beating Olrox.

Solution 2:

You need beat Richter in Dracula's Throne Room (where Richter fought him at the start) by

beating Shaft.

To do this you first need to find two Rings

• The Silver Ring found in the Royal Chapel
• The Gold Ring found in the Underground Caverns guarded by a Succubus

with these you need to return to the Marble Gallery where you first met Maria with the 2 rings equipped

^ (the room Maria is first encounter)

you will meet Maria inside who will give you a pair of Holy Glasses which when equipped when fighting Ritcher you will see something else in the room, attack this and not Ritcher.

after the fight you will automatically find yourself in the Inverse Castle.