Nissa can make turn four or five Eldrazi happen, and not just the turdy cheap ones, things like Ulamog and Kozilek
One or two warriors becomes a whole army, which would be good on its own, but for some reason Wizards saw fit that Najeelas tokens make tokens themselves on future combat steps
Blue Control in Vintage Blue-based control decks have a history in Vintage dating all the way back to the earliest days of the game
A creature with indestructible or a creature that regenerates won't count as having been "destroyed this way." If a creature with flying would be destroyed, but an Aura with the totem armor ability is destroyed instead, Whiptongue Hydra won't count that creature or that Aura as a "creature destroyed this way." Xantcha, Sleeper Agent 1BR Legendary Creature Minion 5/5 As Xantcha, Sleeper Agent enters the battlefield, an opponent of your choice gains control of it
The scry ends up mattering a lot, because you can bottom stuff you dont want