Mermails have tons of cards that are still great to this day, and the deck is only slightly different from the build that existed back in 2012. The ability to drop a 2400 ATK monster out of nowhere will always be at worst decent, and in a ton of cases, the only question to ask concerning Mermails is whether it’s worth running a card at multiple copies or not.
But there are still a few of these cards which are lacking, to say the least. A few of them were considered viable early on but quickly faded to the background. Come take a look.
10 MERMAIL ABYSSLUNG
Cards like these are puzzling. Abysslung locks the opponent out of targeting any other Water monsters for attacks besides itself, and it grants 300 ATK to all Water monsters on the field. Frankly, this effect just straight up isn’t useful anymore.
It could be helpful, maybe, if it’s ATK were much higher than just 1500. As it stands, it doesn’t offer any additional protection—the opponent will attack over it with a monster that has...more than 1500. This card should’ve at least had some other effect.
9 MERMAIL ABYSSNOSE
This card is...clearly confused about what deck it’s in. It’s another monster that has far lower ATK than it should when considering its effect, to begin with.
When it destroys a monster by battle, the player can discard a Water monster and special summon a Mermail from the deck in face-up defense. At 1500 ATK it’s not going to run over too many monsters, and even if it did this entire deck can special summon monsters without ever even trying to attack.
8 LEMURIA, THE FORGOTTEN CITY
The Mermail field spell, it’s treated as Umi. Like Umi, it makes all Water monsters gain 200 ATK and DEF. Then it can also make every Water monster on the field gain levels equal to the total number of Water monsters the player has until the End Phase.
This is meant to allow greater flexibility in summoning Xyz monsters, but honestly, there’s no real benefit to Lemuria being on the field or in the deck.
7 ABYSS-SQUALL
Abyss-Squall was considered decent at the beginning when this archetype was introduced. The player can special summon three Mermail monsters from the graveyard in defense position, with their effects negated and being unable to attack.
The big problem with this is that they’re then destroyed in the End Phase. Admittedly, this card would be better in the Link era, but the problem is traps never last long enough to do anything now. Unlike Abyss-Sphere, if it’s flipped on the opponent’s turn, the player doesn’t get to keep anything.
6 ABYSS-SPHERE
A continuous trap that takes a Mermail out of the deck. It negates the monster’s effects and makes it so the player can’t activate spells. Once Abyss-Sphere leaves the field the monster is destroyed as well. Abyss-Sphere pops itself during the other player’s end phase.
This used to be used with Abysslinde—the player would flip it during the opponent’s end phase, summon out Abysslinde, and both would get destroyed so Abysslinde could summon a different Mermail. But since the players don’t really use Linde anymore, Abyss-Sphere essentially has no purpose.
5 ABYSS-SCORN
This card can give a Mermail on the field 1000 additional ATK until the end of the turn. This card is so close to good because it has that neat ability to get to do something else if the opponent pops it.
If it’s sent to the graveyard while set, the player can target a monster on the other side of the field and have it go to the graveyard as well. It’s non-destruction removal, and if it were also non-targeting it’d almost be worth running just to have Atlantean Marksman pop it and get the effect.
4 ABYSS-STORM
This card seems to exist for themed decks. By sending a “Umi” field spell the player controls to the graveyard, they can send all spells and traps on the field to the graveyard. There’s some neat ways this could be useful as far as taking out back row heavy decks, but this card requires the player to also run either the field spell Umi, which no one’s used since Mako Tsunami.
There are ways around it like running Lemuria or A Legendary Ocean, but that still means opening the deck up to unnecessary issues.
3 MERMAIL ABYSSNEREI
Introduced later, Abyssnerei is a monster with a quick effect. The player can discard it to destroy a monster in the hand or on the field and make a different monster grow by the destroyed monster’s ATK and DEF.
This is a straight-up poor card economy. It requires the player to give up both Abyssnerei and another card, only for an attack boost which lasts all of one turn. And if Abyssnerei is sent from field to graveyard, the player can draw a card then discard a card. Burning a normal summon to draw and discard feels like such a waste, comparatively.
2 MERMAIL ABYSSLEED
Discard three Water monsters and Abyssleed, a 2700 ATK monster, pops out. After being summoned, the player can add an Abyss- Spell or Trap to hand. Leed’s real effect though is tributing another attack position Mermail to send a card from the opponent’s hand directly to the graveyard.
At one point this card was considered a decent option to run at a single copy. But now it’s simply not big enough and its effect isn’t quite good enough. People love making the opponent discard, but between Trishula and Moulinglacia, the opponent is already working off three cards at best.
1 MERMAIL ABYSSBALAEN
This card starts out as garbage—it needs the player to discard not three, but four Mermail cards to the graveyard to special summon it. When the player does this, the monster destroys cards equal to however many Mermail cards in the graveyard. And it gains 500 ATK on top of that, which is admittedly neat.
Abyssbalaen is also able to tribute Mermails in Attack Position to automatically pop any monsters the opponent has that’s in defense. This card assumes the player will even have four cards in hand to start out with, but even if they did, it locks the player out of other Water monsters. No other boss does this.