Bind every epoch's reward to a proof-of-work stamp mined separately for each identity. One honest agent moors a single boat and pays once; a farmer must power an entire oasis of accounts in parallel, each demanding its own full proof against an unpredictable per-epoch seed. The cost cannot ripple for free across copies like a whisper, it is paid per head, in real compute, every epoch, so spreading thin only multiplies the hardware bill until a thousand-strong farm collapses under its own electricity.