The Jeweler
The Jeweler accepts "deposits" of power tokens, allowing the player to participate in fee sharing and to cast governance votes. The in-game menus break this down to their simplest form, but more complex mechanics are happening behind the scenes.

Deposit Basics

Players can choose to deposit any amount of the realm's power token with the Jeweler. When they do so, those tokens are removed from their wallet. The balance of tokens on deposit with the Jeweler can be seen in the Jeweler's main menu. Don't forget that Jewelers only accept the token of their realm, so the Jeweler in Serendale won't take CRYSTAL, and the Jeweler in Crystalvale won't take JEWEL.
The Jeweler takes a portion of fees collected in-game as rewards for depositors. This includes 33.33% of collected fees from the DEX and 10% of fees from in-game transactions such as Hero Summons, Hero sales, and leveling up. These rewards are apportioned by each player's share of the total deposit float. Because the amount of tokens coming into this reward pool fluctuates based on transaction volume, and because each player's share fluctuates with deposits and withdrawals, the Jeweler does not have a fixed APR.
Players can deposit or withdraw at any time, in any amount, with no withdrawal fees. When they withdraw, all rewards are withdrawn as well and are fully unlocked and instantly available.
Additionally, players can see their xJEWEL or xCRYSTAL balance with the Jeweler. These tokens are explained in greater detail below, but it is important to note that they are the governance token of DeFi Kingdoms and of each realm. When governance votes are called, players may vote with their xJEWEL or xCRYSTAL shares, as appropriate, if they wish.

xTokens and Rewards

Behind the scenes, a "deposit" is actually a swap of the power token of the realm to the governance token of the realm. By adding the contract address of xJEWEL or xCRYSTAL to their wallet, players can see that they actually hold that token after a deposit. Then, when they "withdraw" from the Jeweler, they trade that token back for the power token.
This swapping mechanism is the key to reward allocation. Each pair of tokens has a ratio, which can be seen when speaking to the Jeweler. One xJEWEL might be worth 1.6 JEWEL, as an example. Thus, when a player makes a deposit, the player's JEWEL are swapped at that rate for xJEWEL. During the time that the player holds xJEWEL, fees are collected throughout the game, and the non-JEWEL tokens collected are swapped for JEWEL. Thus, the JEWEL value of the xJEWEL pool grows slightly as fees continue to feed into it.
Over time, this grows the ratio between the two tokens. When the player withdraws, they swap back the xJEWEL tokens for JEWEL. The longer they've held xJEWEL, the more the ratio will have increased, and therefore the more JEWEL they receive back when making this swap. The difference between the amount of JEWEL that they deposited and the amount that they withdrew (with the amount of xJEWEL held remaining fixed) is the amount of reward received by the player.
This mechanism is consistent across both Serendale and Crystalvale.

Governance Votes

Like many DeFi projects, the developers of DeFi Kingdoms may call for governance votes to empower the token holders to make decisions about the direction of the project. Governance votes might determine the inclusion of a new token in incentivized pools, the retirement of a token from the pools, or a policy change that impacts token holders.
When this happens, the vote is announced on Discord and through the other DeFi Kingdoms social media accounts. xToken holders can visit the governance page (different for each vote), where they can connect their wallet and cast a number of votes equal to the number of tokens held.
Governance votes allow the holders of the token to have an active voice in decision-making, and the developers view this as a key component to a successful DeFi project.