Swarm is exactly what it sounds like: play a bunch of cheap artifact creatures, hopefully one of which is Signal Pest or Steel Overseer, and attack until you win
In the Arena update that revealed Kraza, we also got to see the Through the Omenpaths take on the Soul Stone
The ability to prevent life loss can also come in handy, although it wont save you from poison counters or commander damage
Making things better, Traveling Chocobo also works as a Future Sight variant for Birds, which should provide a lot of extra value
Inkshield | Illustration by Jarel Threat Damage prevention cards stop damage
Having a second enchant creature on the list is clearly a sign that these decks played things pretty safe as far as two-player games of Magic go, but Grim Reapers Sprint incentivizes you to cast it at a point in the turn where you would expect your opponent to have already fired off their removal spells