Proxy

Proxies were divine servitors of a deity. "Divine" in this case had two meanings. First, all proxies served a deity of at least demigod status. Second, all proxies were demigods themselves, though they weren't so by themselves but only by virtue of being turned into a proxy.

Becoming
To become a proxy, the mortal needed to be physically in the presence of a deity of at least demigod status and needed to be imbued with divine energy from that deity. The energy was just borrowed but immense, enough to elevate the receiver to the lowest demigod status and enough to drop the giver in divine energy by a significant margin. However, the bestowing deity could collect it any time without the physical presence and consent of the receivers and without informing them.

Powers
A proxy boasted the same abilities as a demigod of the lowest rank and had access to some special abilities, including those normally reserved for true deities. What they didn't have were domains and the associated abilities and spells and the ability to grant spells. The ability to sense matters remotely was attuned to their donor deities. While these powers were impressive, they were just borrowed and thus could be retracted at any time.

Rank
Deities viewed their proxies as part of themselves and expected them to be treated the same way the deities themselves were treated.