Looking at the latest patch, we see a shift in the meta, with an additional 7 four-cost units, and one 4 cost unit that some might consider to be "usable" before where it was not (in this case, emerald rejuvniator).

So in total, that is an additional 3 4 cost units per faction to take into consideration when deck building, since two of those units are neutrals.

Kelaino is a 2/5 for 4 unit in Abyssian colors. This is a relatively beefy unit for the faction, when only Juggernaught has health above 4 in-faction at this point in the mana curve. The 2 atk is low (and also puts it in the running as a Zen'rui target), however it can still put up a decent fight, taking 3 general attacks, while also healing your general for 3 if your opponent damages it in 2 damage increments.

Even if it dies directly from combat in this manner during the 'early game' where you would see this kind of thing, it is still dealing 6 damage from counter attacks and healing the general for 3, which is useful for Abyssian, considering many of their decks like to last to the late game where their units and spells shine.

But Kelaino's greatest strength lies in being deployed far away from the fighting, because her ability allows your general to become a tank, and your opponent finds themselves hard pressed to remove it because of her utility in keeping you alive.

Every source of damage is suddenly reduced by 1 if she's out in play. This means that smacking the enemy general with her face is a favorable trade for her. 2 damage for 1, 4 damage for 2, 6 for 3, and so on. Then we consider the opponent attempting to hit you with minions in the early game. Their damage, if they're the 'common' 2/X, means that their attack is effectively halved.

To put this into perspective, with every two hit, Kelaino essentially gets an Arclyte Regalia's worth of effectiveness from it, while retaining 2/5 worth of stats. While she is vulnerable to creature-centric removal, let us also consider what removal effectively trades with her body.

Martyrdom deals with her, but heals the Abyssian general 5, which is a rather hefty cost to the Lyonar player, especially if the Abyssian player already got some milage off of Kelaino's body. Sunbloom can deal with this unit, however it leaves a not inconsiderable body and the Lyonar player will lack that much more dispel removal for units such as Black Solus, Reaper, Reaver, etc.

Egg Morph is a direct trade and eats an attack -if- the Magmar player can get to her. She is a particularly vulnerable target to Natural Selection, but Magmar happens to lack effective ways of pushing against the Abyssian player aggressively at this point, so her usefulness in this match up is already called into question since Abyssian needs no help with it to begin with. Metamorphosis will deal with this card, as well Plasma Storm, however the usefulness of these cards has been reduced thanks to their stats nerfs, and are not particularly effective if played against the Abyssian player if Kelaino is played on curve. And by the point these options are avaliable to them, Abyssian is transitioning to the late game units that Magmar finds themselves powerless to deal with properly.

Chromatic cold will leave it as a 2/3, which is admittedly a good trade for the Vanar player. Hailstone will be a 2 mana advantage for them, however they will be down a card. And since Kelaino has utility on the turn she is played, Hailstone's effectiveness is limited. Aspect of the fox suffers the same issues as many of these removal options.

If you continue to go down the list of removal options currently in the game, the unique position the Abyssian faction finds themselves in leads to this issue with trying to use removal to deal with Kelaino: Kelaino is already in the faction that requires the most removal to effectively deal with, if you're playing another faction. Solus, Reaper, Reaver, Revenant, not to mention potential neutral late game threads such as Dark Nemesis, these are all minions that require removal, and -specific- removal at that.

Solus needs kill spells or needs to trade with a lot of units to deal with the body, Reaper needs dispel, Reaver needs dispel, Revenant needs dispel and/or a kill spell. To add Kelaino as a 4 drop threat to extend the reach of Abyssian's ability to draw the game towards mana timings that are in their favor can shift the balance of the entire meta game in their favor potentially.

Other factions find themselves on the back foot a turn sooner, since they need to deal with Kelaino, otherwise she will extend the life of the Abyssian general past the point where they can recover from. And even if they deal with her, the Abyssian player will continue to drop hyper-efficient threats on curve since they already had to waste a turn dealing with her. Even if she dies, she has fulfilled her job.

The one exception to this particular rule regarding removal is Zen'rui. Zen'rui will turn her into an advantage in your favor, extending -your- life and allowing you to push towards the Abyssian general instead of trading with their units. However, this assumes that you are in range to capture Kelaino, and with the threat of getting her stolen hanging over their head, the Abyssian player will probably be savvy and place her far away from the fighting, limiting the potential effectiveness of this counter.

And up until this point, the synergy that this card has with existing abyssian options has been ignored. Void Pulse is suddenly a heal 4, deal 2. Spectral Blade will heal an additional damage per kill, and will make it much less effective to remove charges with your face. Breath of the Unborn will suddenly heal your general for a good chunk of life as well, and synergizes with the body that Kelaino has. Grasp of Agony suddenly scales into healing as well, Daemonic lure heals your general on top of stalling out a unit your opponent has.

Then if we look at neutral minions such as Eclypse, or Frostborn Naga, or Deathblighter, or even Bloodtear Alchemist, AoE damage and effect damage extends the life of your general by 1 for every single drop of damage, for every single hit, for every single trade.

This will add up quickly if left unchecked. And even when checked, it still plays into the Abyssian player's long term game plan of stalling to their win conditions. This kind of power, extending the viability of when the Abyssian player suddenly becomes a threat, can lead to very tricky situations for other players, and could lead to a much more oppressive format over all, regardless of which kind of Abyssian deck you use.