You can deposit USH in the stability pool and receive profits from liquidated vaults, where the profit is denominated in the collateral. In the liquidation process, an equivalent amount of USH is burned from the stability pool, and then, after fees, the vault’s collateral is distributed to users in the stability pool. In essence, USH is used to buy the collateral under the market rate. Users who deposit USH will also earn HDG rewards. The stability pool helps avoid a spike in the price of USH in a market downturn and also allows for lower overall collateral requirements for vaults.
You can initiate a liquidation and pass in a vault ID, so long as that vault is under-collateralized.