Quote from thatmarkguy »
Nope. Each guild had a pool of eight possible promos that could be the promo in that guild's seeded booster (one mythic and seven rares). So as a result there were some rares that simply could not appear as promos (most notably, the shocks).
Oh, or am I just thinking of the nonpromo rare from the guild seeded pack. Yeah, that may be it.
RtR and gatecrash both had the intro pack rares as the seeded promo and in dragons maze is when the 8 potential promo thing started I believe. However it might have been in khans of tarkir when the system of 8 potential promos started
Edit:the promos for dragons maze were actually just mazes end and the seeded boosters just had a rare or mythic from your guild that was not stamped