The reprint of Mermail Abyssteus in LINK VRAINS PACK comes with a new card text.

Errata

Old Card Text:



自分のメインフェイズ時、手札のこのカード以外の水属性モンスター１体を墓地へ捨てて発動できる。このカードを手札から特殊召喚する。

この効果で召喚に成功したとき、デッキからレベル４以下の「水精鱗」と名のついたモンスター１体を手札に加える。

「水精鱗ーディニクアビス」のこの効果は１ターンに１度しか使用できない。

During your Main Phase, you can discard 1 other WATER monster to the Graveyard to activate this effect. Special Summon this card from your hand.

If this card is successfully Summoned by this effect, add 1 Level 4 or lower “Mermail” monster from your Deck to your hand.

You can only use this effect of “Mermail Abyssteus” once per turn.

New Card Text:



このカード名の②の効果は１ターンに１度しか使用できない。

①：手札からこのカード以外の水属性モンスター１体を墓地へ捨てて発動できる。このカードを手札から特殊召喚する。

②：このカードの①の効果で特殊召喚に成功した時に発動できる。デッキからレベル４以下の「水精鱗」モンスター１体を手札に加える。

The (2) effect of this card’s name can only be used once per turn.

(1): You can discard 1 other WATER monster to the Graveyard to activate this effect. Special Summon this card from your hand.

(2): When this card is successfully Special Summoned by the (1) effect, you can activate this effect. Add 1 Level 4 or lower “Mermail” monster from your Deck to your hand.

The Yu-Gi-Oh! OCG Card Database has been updated with the new card text:

水精鱗－ディニクアビス.

Implication

The errata has changed the (2) effect of Mermail Abyssteus from a mandatory effect, to an optional effect.

When an Atlantean monster such as Atlantean Heavy Infantry is discarded for the cost of activating the (1) effect of Mermail Abyssteus, and Mermail Abyssteus is then successfully Special Summoned, the effect of Atlantean Heavy Infantry and Mermail Abyssteus would form a Chain.

With the old card text, since both Atlantean Heavy Infantry and Mermail Abyssteus were mandatory effect, the player could choose to form the Chain in the order of their choice.

Chain 1: Mermail Abyssteus‘s (2) effect

Chain 2: Atlantean Heavy Infantry‘s (2) effect

By forming the Chain this way, the opponent is unable to activate Ash Blossom & Joyous Spring on Mermail Abyssteus‘s (2) effect.

However, with the new card text, Mermail Abyssteus is now an optional effect, so the Chain can only be build in the following order – mandatory effect first, followed by optional effect.

Chain 1: Atlantean Heavy Infantry‘s (2) effect

Chain 2: Mermail Abyssteus‘s (2) effect

Now that Mermail Abyssteus‘s (2) effect is on Chain 2, the opponent can activate Ash Blossom & Joyous Spring on Chain 3 to negate Mermail Abyssteus‘s (2) effect.

Conclusion

Mermail Abyssteus is arguably weaker now that the player can no longer build the Chain by having Atlantean Heavy Infantry or Atlantean Marksman on Chain 2.

Having Mermail Abyssteus on Chain 2 makes it vulnerable to being negated by Ash Blossom & Joyous Spring and Solemn Strike.