Definitely Dark Souls easter egg :) : r/deadcells

Review: Dead Cells: Return to Castlevania

Video: Top Ten Easter Eggs Of DARK SOULS 3 — GameTyrant

Easter Eggs and References - Dead Cells Guide - IGN

Hollow Knight: Steel Path — Dead Cells introduces Hollow Knight Easter-Egg

Dark Souls 3: 10 Easter Eggs You'll Only Notice On A Replay

This probably has been posted here, but there is a Dark Souls easter egg in the new tutorial area. : r/elderscrollsonline

Review: Dead Cells: Return to Castlevania

Dead Cells Free Update “Enter the Panchaku” Releases on Consoles - Fextralife

Another dark souls easter egg : r/deadcells

Dead Cells Full Dark Souls Easter Egg

Dead Cells Free Update “Enter the Panchaku” Releases on Consoles - Fextralife

Dead Cells 1.0 - What You Need To Know - Cliqist

Breaking Down Each Game In The Dead Cells Crossover Update