Yggdrasil will be a new instance and not see the other cards
The one draft where I piloted this deck, l barely could do all I wanted in a turn even in a 20-land deck
When it dies, you can pay one mana to destroy all the things it has hexproof from, essentially wiping the board
There are 119 multicolour cards: 28 Selesnya (white/green) 22 Boros (white/red) 19 Azorius (white/blue) 15 Orzhov (white/black) Eight Naya (red/green/white), and Mardu (red/white/black) Seven Bant (green/white/blue) Five Jund (black/red/green) Three Gruul (red/green), Abzan (white/black/green), and WUBRG (white, blue, black, red, green) Two Esper (white/blue/black), and Jeskai (red/white/blue)
Effects that allow you to cast a spell for an alternative cost or without paying its mana cost may allow you to apply those to the Omen
For starters, it's quite hard for opponents to get rid of Sensei's Divining Top once you play it, given its built-in tuck myself into the library ability