Harmony Horizon: $100M for Two Stolen Keys
A 2-of-5 multisig guarding nine figures. Lazarus took the two keys it needed, and the bridge-custody era changed for good.
Ronin Bridge: The $625M Heist That Ran on Five Keys
North Korea's Lazarus Group drained Axie Infinity's Ronin bridge of $625M with five forged signatures and a leftover permission nobody revoked.