Vault 87's Evolutionary Experimentation Program exposed subjects to an airborne version of FEV. Rapid physical enhancements accompanied sharp mental regression, and the oldest mutants would become almost feral.

Vault 87の進化実験プログラムでは、被検体は空気感染するように改変された強制進化ウイルスにさらされた。筋肉の急速な増大と精神の著しい衰弱により、時間が経ったミュータントはほとんど野生化する。

生体材料の突然変異

ターン終了時まで、あなたがコントロールしているすべてのクリーチャーの基本のパワーとタフネスはＸ/Ｘになる。

87号避难所的进化实验计划，是让实验对象接触能通过空气传播的FEV病毒。结果他们体能快速增强，心智极度萎缩，就连最年长的变种人也变得无比凶残。

巨量突变

由你操控的生物之基础力量与防御力为X/X直到回合结束。

Biomass Mutation

Creatures you control have base power and toughness X/X until end of turn.

"A regression to ancient forms? A glimpse of future evolutions? Or a fleeting alteration of the present?"
—Vorel of the Hull Clade

Duskmourn: House of Horror Commander

Fallout

Biomass Mutation overwrites any effects that set the power and/or toughness of a creature you control to a specific value. Effects that modify power and/or toughness but don't set them to a specific value (like the one created by Giant Growth), power/toughness changes from counters, and effects that switch a creature's power and toughness will continue to apply. For example, say you control a 1/1 creature that's getting +4/+2 from an Aura, has a +1/+1 counter on it, and is affected by an effect that switches its power and toughness. This creature is 4/6. If you cast Biomass Mutation with X equal to 4, the creature would become 7/9 (4/4, +4/+2 from the Aura, +1/+1 from the counter, then switch power and toughness).

Choosing 0 as the value for X will likely cause creatures you control to become 0/0 and be put into the graveyard.