Blue Vipers

Blue Vipers is a Greenskins Savage Orcs faction introduced in Total War: Warhammer II. It is led by Greebitz Bootlicka and can be found in the northwestern parts of Lustria, between Hexoatl and Tlaxtlan.

Background
Tiktaq'to famously interacted with this tribe:

The cagey Skink Chief also has a keen sense of when to strike and has been known to lead his patrol to victory against forces many times the size of his own — such as when he broke the Blue Viper Savage Orc tribe by having his Terradon snatch up the greenskin Warboss. The Orcs below howled with rage to see their commander lifted thousands of feet into the air only to be let go. The unfortunate greenskin's high-pitched screaming and indignant death utterly broke the tribe's will to fight and they scattered before the Terradons above.

Provinces
Eye of the Vortex campaign: Mortal Empires campaign:
 * Jungles of Pahualaxa (The High Sentinel)
 * Jungles of Green Mist (Spektazuma)
 * Southern Jungles of Pahualaxa (Floating Pyramid, The High Sentinel)

Diplomatic traits

 * Survivor - Defensive and capable, intending to survive whatever comes at them.
 * Underdog - Instead of trying to get to the top of the food chain, this one prefers joining a worthy faction in confederation.

Strategy
If playing as Hexoatl, they are a threat to the south that will inevitably encroach on your territory. Once you have established your two provinces, consider eradicating this tribe to connect with the many Lizardmen to the south.

If playing as Huntsmarshall's Expedition, the Blue Vipers are a deadly foe in the early game. Savage Orcs will make mincemeat of Swordsmen and Spearmen. They also have the physical resistance to shrug off the missiles/artillery Wulfhart usually leans on to win his battles. However, if you can defeat them, you have a safer space away from the Lizardmen and Vampire Coast to develop. It is also possible to link up with the New World Colonies, your only ally usually.

Trivia

 * They are the only Greenskins faction in Lustria, and make heavy use of Savage Orcs.