Lethal Vapors + Encroaching Mycosynth + Damping Matrix

Lethal Vapors

Encroaching Mycosynth

Damping Matrix

How it works

1. Whenever a creature enters the battlefield, Lethal Vapors triggers, destroying that creature.
2. Because Damping Matrix prevents Lethal Vapors's activated ability from being activated, it cannot be destroyed due to its ability.

This clever lock completely halts creature strategies by turning every new arrival into instant fodder for Lethal Vapors, which destroys them the moment they enter. The secret to making this enchantment stick around is Damping Matrix, whose static ability shuts down the self-destruct button on Lethal Vapors so opponents can't just pay zero to sacrifice it and escape. Meanwhile, Encroaching Mycosynth quietly transforms nonland permanents you control (and spells and cards elsewhere) into artifacts, though in this lock's core function, the board simply becomes a lethal gauntlet where no creature can survive.