Venus Weed.

Upon entering a new underground area, you'll find a large vertical room with a dog head sculpture on the right. Below it is a save room. Enter the dog's mouth to proceed.

The next room leads to the Cerberos boss fight.

Cerberos Fight: Cerberos attacks with fast fireballs. You can dodge by ducking, jumping over him, or jumping onto platforms above. The best tactic is to stay close, duck, and attack. He will miss you with fireballs when you are close and ducking.

After the boss room, you'll enter another vertical room with Salem Witches. Be cautious as one of the downward stairs breaks when you land on it.

Proceed to a horizontal room with three paths: left, right, and below. Take the left path first.

In the hallway, you'll encounter flames. Use your shield to walk through them. At the end of the hallway, you will find the Demon Card relic, which allows a demon familiar to fly around and assist you.

Return to the room just above where you obtained the Demon Card. Activate the Demon Familiar, then re-enter the Cerberos boss room. The familiar will fly to a switch in the top-right corner of the room, activating it and opening a new path.

Proceed into the new path to encounter the Venus Weed, a difficult enemy consisting of a female inside a rose with attacking vines. Attack the rose, and distance yourself when the vines attack.

After the Venus Weed room, you'll enter a room similar to the one before the Cerberos fight. On the bottom right is the Ring of Ares (boosts strength, lowers defense). On the left wall, across from the Ring of Ares, is a breakable wall revealing a Turkey.

The next room contains Peanuts and Barley Tea (food items that heal you, Peanuts require an 'Up' d-pad press to consume) and a Power of Sire (powerful consumable).

Leave this secret area of the Abandoned Mine and return to the three-way path.

Take the right path this time, leading to a red door that accesses a teleporter.

Teleport back to Orlox’s Quarters.