Rakdos Lizards is an aggressive creature deck with cheap removal like Burst Lightning and Stingerquill Charm, so Duress strips their interaction before it can be used on your key threats. Strategic Betrayal is an edict, so they choose which creature to exile and you can't pick out Gev, Scaled Scorch or Valley Flamecaller. It is best early, while they have only one or two creatures, and it gets much weaker once they go wide. It also exiles their graveyard. Erode trades for only one creature at a time in an aggressive go-wide matchup with no planeswalkers, and Lunar Convocation's incremental drain is too slow against a deck racing to close the game quickly. Prioritize efficient life-gaining blockers like Hinterland Sanctifier and Enlightened Confidant to stabilize against their aggressive curve.