Since The Sibsig Ceremony destroys your creatures that enter, giving you a 2/2 Zombie in exchange, once you get a second Myr Retriever you can just loop them until you have enough Zombies in play to sweep the board
In Limited, the Exploit here is pretty close to irrelevant, so what were mostly looking at as a two mana 3/3 that does 1 to you ever upkeep
That means that you'll gain tons of loyalty with commonly played Blue cards like Brainstorm, Opt and so on, but not cards like Fact or Fiction that put cards from your library to your hand without drawing them
For this reason, decks of three or more colors are quite popular
7 Wedding Announcement Everyone's invited
Anytime a source of yours deals noncombat damage to an opponent, you get to draw that many cards