Extra Skill Lock

Extra Skill Lock is an effect that invalidates all Extra Skill effects on the target, including Elgif Extra Skills. Currently, this effect is exclusive to enemy skills.

Extra Skill Lock cannot be cleansed by any means outside purging them.

Arena/Colosseum
While not implemented as a buff, Extra Skill Lock effects can passively appear in Arena and Colosseum as one of the Random Rules. In Arena, the Random Rules option must be toggled on.

Elemental Synergy: Nova
Extra Skill Locks can be negated and purged through the use of the Elemental Synergy, Nova.

Interactions with Player/Summoner EXP Effects
If a unit with Player or Summoner EXP Effects is affected by Extra Skill Lock, the player will still receive the benefits of the EXP effects regardless.

This also means units, such as Sweet Harlequin Ellie and Sparkslinger Kagiya, can still Summoner EXP effects on their Extra Skill even if Fire element is not fully max leveled.