*double-sleeving doesnotprotect cards from dragon attacks*
And while he may only enable you to sacrifice one permanent per turn, team him with sacrifice engines like Viscera Seer, tokens or recurring permanents (like Bloodghast or the cat oven combo of Witchs Oven and Cauldron Familiar) to sacrifice, and drainers like Blood Artist and Mayhem Devil, and things snowball very fast
The Sharpie Cube trend originally spread on Reddit, where it has its own dedicated subforum, though it was popularized via a YouTube short by Magic streamer Ashley Bits
The key is how dramatic, obvious, and interesting the error is
The Monarch gets to draw an extra card each turn a huge advantage in the game and some cards also have more powerful effects if youre the Monarch
Being a threat that is resiliant to removal effects is always nice too