Because it'll appear in Play Boosters, you can use Sliver Overlord in Draft or Sealed, although I'm not sure why you would: it's five colors and won't work with anything else in your deck
Look at it in all its glory: In case you happen to be the lucky person who opens up this beautiful collectors item, I have some friendly advice for what you should do with your new most expensive Magic card ever printed. 10
Black handles creatures better than any other color but struggles against artifacts and enchantments
If a player is instructed to set multiple schemes in motion, that player sets a scheme in motion that many times
The actual card Channel is the card specifically banned in commander, but that doesnt affect this cards ability to let you cast a copy
8 Ringwraiths Speaking of how great it is to be tempted by the Ring, Ringwraiths return from your graveyard every time the Ring tempts you