For anyone without the Unreal Editor loaded up, the valid [Tribe] (or animal) and [#] ranges from the PurgeConfigTable are below:
Exile (1-9)
Darfari (1-9)
BlackHand (1-9)
DogsOfTheDesert (1-9)
RelicHunter (1-9)
HeirsToTheNorth (1-9)
LostTribe (1-9)
Lemurian (1-9)
Votaries (1-9)
BlackHandPir (1-9)
Imp (1-5)
FrostGiants (1-6)
Hyena (1-6)
UndeadHighlands (1-6)
UndeadDesert (1-6)
Spider (1-6)
LocustDesertWest (1-6)
LocustDesertEast (1-6)
LocustSwamp (1-6)
Wolves (1-2)
Demonic (1-6)
GrayApe (1-3)
Scorpions (1-3)
UndeadFallback (1-6)
Example Admin Command: StartPlayerPurge Scorpions_Purge_Wave1
You can also use the StartNextPurgePhase and EndPurge commands during the purge to speed things along.