One of the weird parts of Hearthstone for someone coming from Magic is how the positioning of your creatures can end up mattering. I did a draft today and one of my opponents played a card that did 5 damage to a creature and then 2 damage to each adjacent creature. (Creatures stand in a line so there's only one dimension that really matters.) My creatures happened to be set up in such a way that only one of them died as a result while another lost a divine shield and the third took non-lethal damage. But if I'd put them down in a different configuration I could have actually lost nothing at all. If the one with divine shield had been in the middle then he'd have shrugged off the 5 main damage and the other two had enough health to take 2 damage each and live.
Note that auto-summoned creatures (like from a paladin or shaman hero
power) are always put on the very right. If a creature summons another
creature at some point (when it dies, when it comes into play) then it
seems like the new creature gets positioned directly to the right of the
primary creature, not on the far right of your field.
It got me thinking... What cards actually exist that care about the way you position your creatures? What should I be playing around from other people when I don't care about my positioning myself? And what could I actually care about from my end? It turns out there are only 11 cards that I could find that care at all about creature positioning. 4 are harmful from the opponent, 7 are beneficial from yourself.
First, the harmful ones. Hunter has the explosive shot I mentioned earlier (5 damage to something, 2 to the adjacent things). Mage has cone of cold which does 1 damage to a creature and the 2 adjacent creatures and freezes them. Rogue has betrayal which makes a creature do damage equal to its power to the two creatures beside them. And then everyone potentially has access to the legendary card for reaper 4000 that deals combat damage to a creature and any adjacent ones.
I think the legendary can be safely ignored unless it comes into play. Frankly, if he's actually able to attack you're probably screwed since 3 of your creatures are eating 6 damage! I guess if you wanted to play around him you'd put your biggest creature in the middle (so the foe reaper takes maximum strikeback damage) or try to spread out your really important creatures so there are at least 2 other creatures between them as a buffer. For one turn. Since he's sure killing them! But the other three are class specific and each class only has one spell that cares so it should actually be easy to play your creatures in such a way to minimize the impact of those spells should your opponent have them. It seems like the sort of thing you need to think about for awhile instead of blindly tossing guys down and eventually it will become second nature.
For explosive shot it seems like the idea is to minimize the impact of the splash damage. This can be done by sticking the bigger creatures on the outside. He really wants to shoot your 5/5, and if the 5/5 is on an edge then they only get 2 damage instead of 4. Alternatively you could try to clump all your weak things together. That way he likely has to use the main damage on a weak creature, minimizing the impact of the big shot. This is mostly the same thing as above. Big creatures on the outside, little ones on the inside. Divine shield on particularly juicy targets if you have the choice. Note that explosive shot is a rare so you're less likely to see it than other options.
For cone of cold you don't much care about the damage. Your primary concern is what creatures are getting frozen (and therefore what is your opponent going to be able to get away with in the next turn). So if you have 2 important creatures you want them to have at least 2 junky things between them. In draft the important creatures tend to be the bigger ones, so by default you're again looking to have the big guys on the outside and the small ones on the inside. Divine shield positioning doesn't help here I don't think. Cone of cold is a common.
For betrayal you want to be keeping an eye on relative damage/health numbers between adjacent creatures. Ideally you want creatures to not be able to kill the ones beside them, or to really overkill them. The primary creature doesn't take any damage at all so in one sense putting your big guys in the middle means they're less likely to take damage. Unless you put 2 big guys beside each other, and then one can punch the other. So once again you probably want the bigger creatures on the outside. Betrayal is also a common. But I know from experience with the card that it's really awkward to use. You should still play around it because why not?
One thing I haven't mentioned yet is making your creatures untargetable. Creatures in stealth or ones with an ability saying they can't be targeted make fantastic creatures to put in the middle. If you find yourself in a position where you probably can't lose unless they have explosive shot and you have a stealth spare part you may want to put it on the lynchpin of your line.
On the other hand you have the creatures that care about your own setup. Some of these are pretty mediocre, others are really good. The key thing to keep in mind is the buff creature will go between the two creatures they're buffing so you want the crucially buffed creatures to be together. You also want to make sure you keep creatures on both sides if they have a continuous effect. This is particularly important for shamans and paladins, and is handled by playing real creatures on the left and letting new totems/recruits go on the right.
Wee spellstopper is a mage epic that keeps adjacent minions from being targeted. She can still be targeted though, and if the enemy has one of the above spells it's a little unfortunate since she's presumably protecting important creatures that you don't want splashed into!
Flametongue totem is a shaman specific basic card (which I think means common in drafts) that gives adjacent creatures +2 power. It's really powerful and setting up your board to make optimal use of it seems really important. One trick to keep in mind is if you attack with a buffed creature and it dies then the line shifts together and a new creature gets buffed. This can let you trade up a lot of creatures really efficiently! Especially since shamans can end up with a bunch of 0/2 totems in play. Having them all turn into 2/2 bombers can be really good!
Dire wolf alpha is a general common which does the same thing as flametongue totem, except it only gives +1 power. It's still really good and everything kept in mind for flametongue is important here too. Another trick is that you can buff up 0 power creatures to allow them to attack... Like a nerubian egg! Dire wolf alpha gets a lot more important for your deck if you have eggs.
Void terror is a warlock rare that destroys the adjacent creatures when it comes into play in order to absorb their stats. I have no idea how to make optimal use of this guy. You do destroy the creatures so any deathrattle effects will proc immediately. Temporary buffs (power overwhelming, abusive sargeant, dire wolf alpha) get counted as well, and then the void terror can get the dire wolf's buff for itself!
Sunfury protector is a general rare that gives adjacent creatures taunt when it comes into play. So it cares about your setup only on the moment when you play it. You want to taunt up creatures that you want to take attacks and avoid taunting up creatures you're trying to protect. So having your board be egg, flesheating ghoul, egg is a terrible idea. If you have sunfury in your deck you want to be mindful of keeping prospective taunters together.
Defender of argus is a general rare that works the same as sunfury protector except it also gives +1/+1 on top of the taunt. So there's more to keep in mind because you need to balance who you want to buff with who you want to get attacked.
Finally there's ancient mage which is a general rare that gives adjacent minions spell damage when it comes into play. I'm really not sure why you want to do this. But if you actually have a plan for spellpower then you want to get these buffs onto harder to kill creatures and off of taunters. So clump your tougher non-taunters together I guess.