Okay. So. Balloon will appear every 20 mins, so imagine it is 12:00 - you usually playing and by the 12:20 you have 0.001 wager - the balloons appear and one will have 30% rake back - 1% house edge multiplied by 0.3 (30%)
If by 12:20 your wager is below you won’t see balloons
There three balloons so if you guess wrong one - no bonus
there will also be rains today too, giving you a chance to get in on the bonus without deposit!