The easiest way to determine if your deck belongs in bracket four or five is that four is an optimized commander deck, while five is a deck you would bring to a tournament with the intention to win
I would generally value the bonus milling at zero or perhaps even a slight negative if it risks helping out my opponent, however, so the base effect must really be strong enough
Its helpful that this deck is a bit slower out of the gate because you can then discuss with the table what would be good cards for you to remove once you get your commander out
Seven mana is a big ask, but in combination with Sun Titan, Karmic Guide, Burnished Hart, Solemn Simulacrum and Fetchlands, you can recur your whole board constantly
Flood insurance, velocity, aggression, evasion, graveyard synergies, playing around mass and sorcery speed removal
It features a prismatic, rainbow-like shimmer that appears when the card is tilted under light