"Telemetry indicates that the calibration of Normandy's weapon accuracy could be increased by .32%."
"You couldn't squeeze .34% out of it?"
"Negative. That threshold is impossible."
"You sure? Take a look now."
"Scanning. Normandy's weapon systems have been improved by .43%. How did you accomplish this?"
― Legion and Garrus (Mass Effect 3)

The power to manipulate the efficacy of anything. Sub-power of Causality Manipulation and Probability Manipulation.

Also Called

  • Effect Manipulation
  • Efficiency Manipulation
  • Proficiency Control


User can manipulate the effectiveness of anything/everything, allowing them to increase or decrease the potency of anything and control the probability or improbability of something happening.




  • User only controls the potency of abilities, cannot permanently limit or negate them.
  • Efficacy without Efficiency means that the effect one desires might not happen at that specified time.

Known Users

  • Hades (CDZ)
  • Scorpio Milo (Saint Seiya)
  • Shishio (Hitokiri Batosai)
  • Mizuro (Combo)
  • Wanda Maximoff (X-Men: Evolution)
  • Saechika Hachiouji (Code:Breaker)
  • Shion (Tensei Shitara Slime Datta ken)
  • Rimuru Tempest (Tensei Shitara Slime Datta Ken); via Gluttonous King Beelzebub

Known Objects

  • Galaxy Police Body Enhancement (Tenchi Muyo! GXP)
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