Great breakdown on the airdrop cards, if I were to rank them I would take Baakjira as #1 due to its defensive ability and slow ability, it will make the opponent slower while making your Deck faster with Kelya, I can see that the new meta would be Speed, so I am pretty optimistic with Baakjira, 2nd would be Grum, man Bloodlust is definitely an ability to be reckoned with, it cannot be taken lightly, plus having magic defenses just made it even better. Lira would be third, I can see a good spot for death running speedy lineup, which could be meta changing for death splinter, Uriel as 4th, I have nothing to say about this, and last would be Iza, I don't really think Iza would be card to play aside from maybe little league.
!1UP
Lira is maybe the most interesting one in my opinion. As you say, a speed death deck is quite possible as they do have many fast cards (soulstorm, phantasm, Sha-vi, Pelacor Deceiver, Riftwing). Might combine with Supply Runner to gain another swiftness. Two of those are flying and with backfire, which can make things interesting!