Challenging an Ante Test expresses belief that the tested guarantee could/will fail.
You will pay "decay" fees to stakers over time to challenge a test.
However, if the test fails, you can claim a portion of staked funds as a reward.
Failed tests reward challengers for identifying risk in the system
Your challenged funds will undergo continuous decay over time (by default, this is 100% per year). Some amount of this may be claimed by the test author; the rest is allocated to stakers.
Challengers in a pool can check the underlying test at any point. If the test fails, the pool is locked and staker funds can be claimed by challengers.
5% of total staked balance are allocated to the challenger that made the failing test check. The remaining 95% of staker balance is distributed amongst all eligible challengers:
You have 0.5 WETH challenged in a test when another challenger triggers test failure. Staker balance is 20 WETH and total challenger balance is 1 WETH.
Tip: Don't want to do math? Each pool has a "payout floor" like 1:10. This serves as a soft floor for potential payout on test failure: for a 1:10 payout floor, for every 1 ETH you challenge you could potentially get 10 ETH on test failure.