Abyss-scale of Cetus

[Regarding "Can only be equipped to a 'Mermail' monster"]

This is not treated as an effect. It is a condition for which monster this card can be equipped to.

You can activate this card by targeting 1 face-up "Mermail" monster in your Monster Zone.

[Regarding the effect "The equipped monster gains 800 ATK"]

This is an effect that does not start a Chain Link, applied by this card while it is face-up in the Spell & Trap Zone.

This is an effect applied to the equipped monster.

Regarding the effect "As long as this card remains face-up on the field, negate the effects of Trap Cards activated on your opponent's side of the field. Then, send this card to the Graveyard": * This is an effect that does not start a Chain Link, applied while this card is face-up in the Spell & Trap Zone. * While this effect is being applied, if your opponent performs the resolution of an effect of a Trap Card activated on the field, that first instance is negated by this effect. * This effect is also applied during the Damage Step. * The effects of Counter Trap Cards activated by your opponent are also negated.