BurnSet

Event Re-added v101 → v127, v133 → v219, v233 → v247, v252 → v265, v273 → v277, v290 → current #36

Emitted when burn registration cost is changed.

Useful for: minersvalidatorssubnet ownersanalyticsdevelopers

The Big Picture

Burn registration is the 'fast' way to join a subnet - you pay TAO instead of solving POW puzzles. Despite the name, your TAO isn't destroyed - it goes into the subnet's liquidity pool (SubnetTAO), and the Alpha received is burned. The burn amount is the exact TAO cost. Burn normally adjusts with registration demand, but this event fires when it's manually set. This is a key economic lever.

Why This Matters

Burn registration cost directly affects your bottom line. If you're registering via burn, this is the TAO you'll spend (it goes to the subnet's liquidity pool - you can't get it back). A lower burn means cheaper entry. Timing your registration around burn drops can save significant TAO.

Example Scenario

Subnet 5 has a current burn of 0.5 TAO. Demand drops and the subnet owner adjusts burn to 0.3 TAO. BurnSet fires with the new amount. If you were waiting to register, this is a good time - you save 0.2 TAO per registration compared to before.

Common Questions

Does burned TAO go anywhere useful?: Despite the name, TAO isn't actually destroyed. It's swapped into the subnet's liquidity pool (SubnetTAO), and the Alpha received is burned. So TAO stays in the ecosystem while Alpha supply decreases. The TAO becomes available for others to swap out.
How does burn compare to staking for registration?: Burn registration puts your TAO into the subnet pool (you lose it). Some subnets allow 'stake registration' where you stake TAO instead (you keep the stake). Check if the subnet supports stake registration.
Can burn ever go to zero?: It's bounded by MinBurn (floor) and MaxBurn (ceiling). Check the subnet's MinBurn to know the lowest possible cost. A MinBurn of 0 is rare - most subnets have some minimum.

Use Cases

Monitor registration cost to time your registration
Compare burn vs POW cost-effectiveness
Track burn trends to predict future costs
Alert when burn cost changes significantly

How to Use This Event

→ Track burn on subnets you want to join
→ Compare burn across subnets to find cheaper entry points
→ Monitor burn trends for economic analysis

From Chain Metadata

setting burn on a network.

Triggers

Preconditions

Caller has admin/sudo privileges
New burn within MinBurn and MaxBurn bounds

Effects

Postconditions

Burn amount updated for subnet
New registrations must burn updated amount

Side Effects

Changes TAO cost to register via burning
May shift preference between POW and burn registration

Event Data

#	Name	Type	Description
0	arg0	u16	Event field #0 (u16)
1	arg1	u64	Event field #1 (u64)

Code Examples

import { ApiPromise, WsProvider } from "@polkadot/api";
import { stringCamelCase } from "@polkadot/util";

const provider = new WsProvider("wss://entrypoint-finney.opentensor.ai:443");
const api = await ApiPromise.create({ provider });

// Subscribe to BurnSet events
api.query.system.events((events) => {
  events
    .filter(({ event }) =>
      event.section === stringCamelCase("SubtensorModule") &&
      event.method === "BurnSet"
    )
    .forEach(({ event }) => {
      console.log("BurnSet:", event.data.toHuman());
    });
});

Version History

Version:

v101 block 1 2 args

v133 block 1,404,224 2 args

v233 block 4,920,350 2 args

v252 block 5,163,656 2 args

v273 block 5,659,032 2 args

v290 block 5,947,548 2 args Current

Runtime Info

View Source

Pallet Index: 7
Event Index: 36
First Version: v101
Current Version: v393

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