There's been a lot of talk regarding Faceless Summoner. Some think it'll just be a solid card, others expect it to be just as troublesome as Piloted Shredder has been for years. So we decided to stop and take a look at the stats behind the card.
As far as the minion itself goes, a six mana 5/5 is generally overcosted. To this day, Boulderfist Ogre still remains the most effective example from a pure stats perspective with 13 for only six mana, three more than what we're getting with the Summoner. Goblins vs. Gnomes had Piloted Sky Golem which also sacrifices the three stats for a very powerful Deathrattle, but due to the fragile nature of the card, it very rarely sees any play at all. Drakonid Crusher has a strong, but conditional Battlecry which can be silenced off of it, but like Boulderfist, it simply isn't enough to make the cut in today's popular archetypes. Unfortunately for it, Master Jouster suffers from the Jousting effect which really does knock it down a peg despite having 11 points of stats alongside a potential Taunt and Divine Shield buff.
To put in perspective, perhaps the most equivalent minion in all of Hearthstone is Emperor Thaurissan himself. The same stats, the same cost, and a very powerful effect - the only difference being he's a problem turn after turn. Sylvanas Windrunner also makes an argument for comparison, again with the exception that she can simply be eliminated by trading all your minions away, keeping her from stealing anything. Faceless Summoner's extra minion won't go away since it's preemptive.
Now let's take a look at the field of three mana cost minions and how they average out.
After putting all of the 3-Cost minions into a spreadsheet, not including the latest Old Gods cards, we find that the average drop from this Battlecry is currently a 2.7/3.0 in Standard and a 2.6/3.2 for Wild.
That said, we're looking at a 6-Cost 7.7/8.0 for a total of 15.7 stat points - well above that 13 point benchmark set by Boulderfist Ogre. The main difference here is that it's not all allocated on one minion, your opponent will have to deal with both. In addition, there are plenty of three drops that have beneficial effects like our buddy Brann Bronzebeard.
The normal measure of how good a card truly is usually takes into account how many "bad" results there are - like Piloted Shredder's Doomsayer. But the three mana cost minion spot has very, very few landmines to avoid, even more so in Standard where certain problematic cards like Dancing Swords, and to a lesser extent Deathlord, are already off the table. In fact, Coliseum Manager is really the only "bad" minion you could get and even then it's only a problem if you really need it to stay on board but have to use your hero power.
While we're not yet accounting for any cards from the upcoming Whispers of the Old Gods set, there's still worth in looking at some of the mechanics that can pop out of your Faceless Summoner for some added value. We've found that in Standard there's approximately a 32.7% chance (36.8% in Wild) of the minion it drops having a helpful mechanic attached to it. A 1/3 chance of spawning something that's even more troublesome for your opponent already shows the value of this card. This will most certainly change with Old Gods, especially considering many of the cards we have yet to see are commons that are likely to dilute the pool a bit. But overall Faceless Summoner is a very, very solid addition to the Mage arsenal. For a look at our stats, check out the tables below.
Extra Value (Sorted by Likelihood)
Draw stats obtained from Hearthstone Labs.
2.7% or one in every 38 draws for a non-situational Aura
2.7% or one in every 38 draws for a useful Inspire
2.2% or one in every 46 draws for a non-situational Aura
2.2% or one in every 46 draws for a useful Inspire