Each class (monsters included) has player rankings by kills.
Tier 0 (purple chat + in-game title, earn SP at 3x rate) — top 1% of player population
Tier 1 (blue chat + in-game title, earn SP at 2x rate) — top 5% of player population
Tier 2 (green chat, earn SP at 1x rate) — top 20% of player population
Seasons last for 90 days. Each season brings new weapons, armor, skins, chromas (and potentially classes). Rankings are reset at the end of each season.
$10? Access to the season’s challenges/quests to unlock items, skins, chromas, emotes
20 levels (corresponding to challenges/quests), each unlocking something. If all levels completed, big unlock.