Voidmaw in Steal an Egg

Voidmaw is a Rift pet (Mythic rarity). Rift pets do not come from a zone nest: they are obtained through the Rift event — timed Overlord fights every 30 minutes, the Boss Shop, Boss Mastery rewards, or the permanent Rift, which rotates through three egg banners roughly every 3 hours.

The wiki lists its base income as $50K/s, which ranks it 15th of the 17 Rift pets by base rate — Shattered Colossus tops the Rift group at $3.5B/s. Base rate is what a normal-size, un-mutated hatch earns; everything above that comes from the size roll and the colour mutation.

With a colour mutation and no size bonus, the same Voidmaw would earn roughly: Silver ×1.2 ≈ $60K/s, Golden ×2.5 ≈ $125K/s, Rainbow ×3.5 ≈ $175K/s (multipliers from the wiki's Mutations page; arithmetic is ours). Add a Giant (×3) or Huge (×5) size roll on top and the numbers multiply again.

Neither a hatch reward nor a grow time is recorded on the wiki for Voidmaw yet; if you have hatched one, the timer on the pen and the reward pop-up are the two numbers worth noting.

Mythics are the eggs other players come to steal. Bear traps around the pen are the cheap insurance (max 3, 7-second hold).