Until end of turn, that player can't cast spells, you may look at the top card of their library any time, you may play the top card of their library, and you may spend mana as though it were mana of any color to cast spells this way
Nykthos, Shrine to Nyx Nykthos, Shrine to Nyx works well in most mono-color decks, so long as you are running a lot of permanents
Spinner of Souls is a powerful Spider, with relatively weak defenses, compared to the average Spider
The Goblin Matron can help you make that happen
Then that five-cost artifact will choose the two on arrival in colorless but a bit pricey too, as a heads up
The Mythical Island version has an attack called Leap Out that simply swaps the card for one on the bench