This allows, for instance, several damage-doubling replacement effects to stack multiplicatively, or for a friendly replacement effect to reduce incoming damage before the opposing replacement effect doubles it
You can cast another spell before any player can attempt to remove Omniscience with spells or abilities
Paul's card was the only one of those to have been graded as a 10 by PSA (Professional Sports Authenticator), which rates the conditions of trading cards, meaning it is a "virtually perfect card"
On the other hand, and perhaps this was hinted at in my initial post, it is harder to draft slow decks, since there aren't really any obvious 'this goes in defensive decks'-cards, as virtually every tool can be used in an aggressive manner (like real tools!)
Even just one or two dragons with double strike can turn combat into a complete bloodbath, and if your deck is packed with flying threats, Atarka ends games almost out of nowhere