feat: the abyss

[trufitus]

Things that still need to be done when this gets merged into a release due to missing content in the current branch:

• Pickaxe check in the rock obstacle;
• Axe check in the tendrils obstacle;
• Entrana rift needs to check for combat gear;
• Abyssal guardian uses a magic attack if attacked directly (similar to dark beasts);
• Restrict telegrabbing pouches with the message The pouch is too insubstantial to telegrab.;
• Destroy pouches on death;