Balance decisions that dont make sense
Let me preface this with the understanding that everything is viable if you get lucky on draws. Im speaking from a normal game perspective..where you dont have golds early.. you dont get all the things you need immediately, and you dont get just the right item drops to optimize your best champions. That being said:
Why do demons drain mana? If you ever stack 6 demons you have a 70% chance to drain mana and do bonus damage. The bonus damage is nice and all but it isnt huge, and draining mana is a great defensive ability..but look at the demon lineup. Varus, Morgana, Evelyn, Brand, Elise, Swain, Aatrox. These are not champions designed to be tanky. Some of them are somewhat durable but this is very much a damage dealing lineup. The end result is that a stacked demon team is not viable. They arent tanky enough to really make use of the delay/damage mitigate that their mana draining provides. This is a team that would be much better served by a straight damage dealing bonus, or a much more significant durability bonus.
On the other end of the spectrum.. Knights have an alright bonus but it quickly becomes useless as the game progresses and higher end champions get by on the strength of their spells rather than their autoattack. Why build 6 knights when, by the time you have them, they are completely outclassed by pretty much everything they go up against? Both of these factions would really benefit from some kind of "capstone" when they reach 6. Demons could perhaps benefit from a "cant be crit" at full power, as it would allow them to both be a counter build to full assassin, and also provide them with a bit more durability. Knights could perhaps use "Reduces spell damage against all allies by 50%" so that their fully stacked durability actually feels like durability after round 20, and it would also extend to their allies, which they will need one or two of to provide damage for them, since their's is abysmal.
Items.. they are probably the most important aspect of the game. The biggest deciding factor in who wins, yet they are also the most RNG based part of the game. There really should be mechanics in place to insure everyone gets access to at least a somewhat equal amount of items. A guarantee of 1 item in every NPC round, with a chance of having two drop, seems like a good system that wouldnt be all that difficult to implement. Also, NO ONE wants the chain vest. There are quite a few items in the game right now that I would label as "absolutely worthless". Phantom Dancer, Locket, Frozen Heart, Cursed Blade, Ludens... many of these under performing items build off of the chain vest. Negatron is also pretty bad, but Bloodthirster builds off of it so it isnt entirely bad. Id say at least a third of the buildable items could use a complete rework/replacement.
Finally... Phantoms. What a horrible idea this was. First of all, the phantom synergy..reducing one champ on the enemy team to 100hp..is basically just saying "instantly kill one enemy champion". You get this wonderful ability for the low cost of just TWO phantom champs. Kindred and Karthus are both amazing. Mord isnt bad, and can be built from turn one. This is a problem. The synergy is too powerful, too easy to include in any comp, too easy to get, and is 100% not fun 99.999% of the time. For the person going up against it, it is pretty freaking lame when your strongest champ, who your entire team is dependent on, gets removed from the match in the first 3 seconds because the other guy got lucky. It is also lame when you have the synergy on your team and it takes out the 1 star braun that the other guy only has so that his gold ashe gets the glacial buff. Incidentally, this buff is powerful enough that when you combine it with the benefits your team gets from having Kindred or Karthus on the team.. it quickly makes these champs seem overpowered.
Thats what ive got for the moment. Overall im enjoying the game mode, but i find myself thinking to myself "this will be really fun when they fix all the issues with it" about a dozen times a night.