Hearthstone: The 20 best legendary cards

Despite its madcap explosive theme, The Boomsday Project hasn't seen that many brand new decks blow up. That said, on close inspection the expansion has had a wide-ranging effect on many of the most powerful decks already in the format. Probably the biggest winner from the new set has been Odd Warrior—it turns out that Dr. Boom looks after himself—which has had the knock-on effect of rejuvenating Quest Rogue, it's natural counter. Elsewhere, Paladin has been pushed out as the preferred aggro deck of choice.

Since we last updated our list, there has also been a balance patch which changed several cards. As a result, Sunkeeper Tarim has taken a double hit from the changing meta and the nerf to Call to Arms. For the time being he's gone from second spot in the list to vanishing completely off it. Some Control and Even Paladin archetypes have started to emerge however, and it seems unlikely that he’s gone for good.

As you'd expect, our ranking is largely governed by raw power, but it's also intended to help you use your dust as efficiently as possible. Consequently, neutral cards tend to score higher, because they generally offer the most potential return on investment. The cards towards the top should all be considered safe crafts, but bear in mind that I can't see the future (yet), so potential balance changes to come—though none seem imminent—may shake things up. If Giggling Inventor eventually falls to the nerfhammer, for instance, a very different meta will unfold.  

#20: Stargazer Luna

Luna opens up a wealth of possibilities for the Mage class. Her ability enables you to draw a card each time you play the rightmost card in your hand, potentially setting up crazy draw chains that are reminiscent of Miracle Rogue at its most degenerate. If you can couple her with a Sorcerer's Apprentice or two, Luna becomes one of the most menacing cards in the game.

At first glance, the downside of having to keep playing cards from the top of your deck seems like it would be prohibitively impractical. The reality is that Luna can generate huge bursts of damage in decks that run enough low cost spells. Her effect is so devastating that most Burn Mages have dropped Pyroblast to ensure it doesn't interrupt Luna when she's on a roll.

Most opponents have learned to immediately destroy Luna as soon as she enters play, but the card can be held until later turns to set up some surprise wins. With no easy counter to that plan (RIP Dirty Rat), it feels likely that Luna will be Mage’s star of the show for an astronomically long time.

#19: Zilliax

It is fitting that Zilliax has taken the place of Bloodmage Thalnos, as there are similar reasons why both cards are strong. Zilliax has quietly found its way into multiple deck archetypes without being a particularly dominant performer in any of them. 

Like Thalnos, Zilliax does multiple things well. It offers a Hail Mary line of healing and can often remove two minions while gaining at least six health. That's more than enough for many slower decks to stabilise, so it's no surprise that the first home it found was Odd Warrior. Since then, Zilliax has made its way into Mech versions of Deathrattle Hunter and also Mech Paladin, which can capitalise on the Magnetic ability.

With Zilliax being such a versatile neutral card, the only thing stopping it from being in even more decks is the stiff competition for the 5-Mana slot, particularly in the form of Giggling Inventor. Going forward, should Giggles suffer an unfortunate accident at the hands of the balance team, this mech will become an even more attractive proposition.

#18: Sonya Shadowdancer

Sonya’s ability is great when you're ahead on board, but from behind she risks being played as a vanilla 2/2 for 3 Mana. This means that her natural home is in tempo decks, as they tend to be in front early and then run out of cards rapidly. Although viable in such decks, the downside turns out to be a big one, and so Sonya has fallen out of favour in pure tempo decks.

Luckily for people who opened Sonya, or crafted the card a little too enthusiastically, she has carved out an extremely important role in Quest Rogue decks. The ability to play her and then sacrifice several Stonetusk Boars or Southsea Deckhands means that you can rapidly complete the Quest. Early board presence is rarely important in Quest Rogue, meaning she can be saved to use as a vital combo piece. If you have any interest at all in that archetype, Sonya is a must-craft. She also has the potential to turn up in other decks in the future.

#17: Aluneth 

The flavour text on Aluneth is one of the most accurate descriptions in the game: “PHENOMENAL ARCANE POWER… itty bitty living space”. Although the Mage weapon has been on this list since the Kobolds and Catacombs expansion, there still isn’t a better way to sum up the card's strength. 

Aluneth enables you to keep the burn damage coming—and despite the removal of Ice Block with The Year of the Raven rotation, Tempo Mage decks have continued to take advantage of Aluneth. It is also a card that feels like it would be natural in combo decks, but this is where the itty bitty living space comes in. It is usually very difficult to keep your hand empty while accumulating combo pieces, and as of yet no combo deck has made the card a mainstay.

Tempo Mage has become a reasonably narrow, if strong, archetype in recent times, which has led to Aluneth falling down our list. However, for aggro players, Aluneth’s phenomenal arcane power still represents a sound investment.

#16: The Soularium 

Drawing cards in card games is, oddly enough, a good idea. The Soularium delivers potent card draw at a very low cost. Due to the fact that the cards have to be played on the same turn that The Soularium is played, it narrows the scope for potential combo decks. Where the card is a natural fit is in Zoo decks, which play enough cheap cards that you're usually able to spam several immediately.

But why does Zoo even need card draw? After all, the Hero Power does that perfectly well. Well, because it turns out that Zoo running Happy Ghoul is such an explosive deck that the reload provided by The Soularium can keep an immense amount of pressure on your opponent, especially after the first board you build is cleared off. It's also perfect when you want to dig for a Soulfire or Doomguard to deliver that last bit of face damage.

Despite being a very powerful card, The Soularium sits rather low on this list, and that's due to its narrow usage. Zoo has previously been a safe haven for cheap beginners' decks, and The Soularium adds another expensive legendary. If you enjoy Zoo and want to improve your deck, The Soularium will bring sunshine for many months to come. But you can also get away without running it and still have a perfectly serviceable deck. 

#15: Azalina Soulthief

Azalina was a fringe card which started seeing serious play after Blizzard made a change to the way card copying effects work. Now that copies retain any buffs that the original has in hand, Azalina has become a potent tool when used in conjunction with Control Warrior's armor gain Battlecry effects. Played at the right time, the Warrior is able to copy 1-Mana Shudderwocks in order to gain more armor than the Shudderwock can ever do damage.

Following that increase in play, Azalina started turning up in other decks—for instance, Hunterace experimented with her in Malygos Druid as a reload for control matchups. Games with Azalina are complicated because you need to pick the perfect time to play her. And of course, she also gives both players complete information about each other's hands—a sizable advantage for the more skilled player. The rope also means that Azalina games tend to include many mistakes. If you craft her, be sure you're ready to run those risks if you want to be the soul survivor.