mtg cards like howling mine What Magic have similar effects in red, blue, or colorless? so you don’t lose it and can come back anytime after! Howling Mine - High Quality

The Onion Knight also cannot equip any abilities nor learn any skills of its own so it's limited to only using the basic physical attack with all the downsides of that

Anything can be used to represent a token, but there are also official tokens to correlate to the tokens cards create

Since it deals damage, All Will Be One can go infinite with cards like The Red Terror and Night Dealings, as they get a counter whenever damage is dealt to a player or permanent, which will then cause All Will Be One to trigger again, creating a loop that can do infinite damage

Ive been tweaking and tuning that deck, and I always had the issue that it was too strong versus precons, but too weak versus tuned decks, and part of that issue was the tapped Zombies it makes