Participating in Sparklet Warz must be done through burning a Sparklet Warz Legits Pass. They can be purchased directly from the Upland Store ($5), or from players selling them in their variety legits metaventures. When purchasing a pass from Upland, the faction is randomized. If you did not get one that you want, you might be able to trade with someone in the same position as yourself. Alternatively, you might be able to find them on sale in metaventures. The first pass you burn will be the faction that you will be a part of. Burning additional passes is simply a waste.
Each round of Sparklet Warz will have its own pass, so there holding a pass from a previous round will not provide you with entry to future Sparklet Warz. You will have to purchase the new pass each round.
Burn Sparklet Warz Pass by Upland Guide