This is my first attempt at looking at the relative powers of Altered cards. I did a very rough examination of all the commons in the demo decks and it was clear from the vanilla cards that the relative power level was grouped around the number 3.
To explain. A 3/3/3 is (on average) costed at 3 mana. So every 1/1/1 boost token is worth 1 mana orb. If the stats of the three biomes add up to less than 9, then the character will have some kind of additional ability to bring them up to around the power level of the equivalent level of 1/1/1 stats. If the stats are greater than they should be, it will have a downside that will bring it back to that core pointing system (on average). Bravos Pathfinder is a unbalanced biome card but add up its stats and dive by 3 to give the expected mana cost (which is pointed at 2).
Now my initial pointing of the commons relies on some guesses as to what the abilities are costed at. However some of the abilities are obvious. A boost will on average give a 1 extra mana cost. My working from basic principles on others is given below.
So a create with 3/1/3 biome stats would be undercosted for 2 mana and overercosted at 3. So it would likely have an extra ability to make it cost 3. An example of this might be to give it Sabotage when played from the hand. So next we need to examine the value of that ability.
To answer that, we need to first of all take a look at what Equinox values as the cost of a card. Generally a card can be played twice. Once from the hand and once from the reserve. (Let's ignore Fleeting characters and Anchored characters for now). It is clear from Tooth Fairy that they cost the sabotage effect played from hand as 1 mana. Tooth Fairy is a 1/1/1 which would normally cost 1 (which it does on the reserve cost) and the extra 1 on the play from hand side (which has the sabotage effect). This means Sabotage costs 1 mana for each instance of use. The same is true on the hand cost of Haven Bouncer.
What about card drawing? Baba Yaga has stats of 1/2/1 and a hand play ability of draw a card. The stats of the 4 should cost 1 and a third mana which we need to pay on both sides of the card (2 and two thirds mana). SInce the back cost (without the card draw) costs 2, this means that 2/3 a mana is a tax from the front side of the card to replay it. So the cost of that card draw on the front is 1 2/3 additional mana on the front end and 2/3 mana on the reserve cost. This gives us a card draw cost of 2 1/3 mana.
To look at fleeting we have a good example in Bravos Tracer. A 3/3/3 using the normal costing system would normally cost 3 mana. Here we see the Tracer only costs 2, which means that the fleeting ability must give a discount of 1 mana.
Dorothy Gale will similarly enable us to cost the Send target Character to the Reserve ability. He stats of 3/2/2 add up to 7, which should cost 2 and 1/3 mana. Since she costs 5 on the way in from the hand and 3 from reserve, we have the 2/3 mana for the ability coming from the reserve side and 2 and 2/3 mana from the hand cost. This makes the ability cost 3 1/3 mana.
Sabakaru clearly shows us that the cost of sending the opposite expedition back is 3 additional mana on the 4 cost that 4/4/4 biome strengths should cost (I rate that one as a bargain compared to Dorothy above by the way).
Gift appears to have no cost attached to it. Kitsune is a 1/1/1 for 1 mana which is the normal cost for these stats. Having gift doesn't increase the cost on Kitsune, so we can take from this that Gift costs zero (which given it affects yourself and your opponent seems reasonable).
Atlas can help us cost the Gigantic ability. Atlas gives a total of 6/6/6 stength over the two expeditions which if we divide by 3 should cost 6. However if we look at the card it only costs 5. This means that the gigantic ability costs -1 mana since it is a disadvantage to having 1 card that can be more easily removed that having two separate 3/3/3's.
Anchored is a little harder to cost. We can look at Sneezer Shroom for costing this one. The Anchored ability here makes the 1/1/1 last an extra turn on both sides. Effectively it is giving us 2/2/2 worth of stats for each cost and therefore costs 2. So the Anchored ability here is costing us 1 mana on each costing.
Note that the formula for costing is much more complicated that I've given above. Daughter of Yggrisil seems massively undercosted given the above and Coniferal Coneman seems to have an Anchored cost of 2. So Anchored probably scales with the size of the creature stats in terms of additional mana cost.
From using these basic principles of working out the costs of abilities we can then apply this to all the cards and work out whether the actual mana costs on the card are over or under this cost curve. I still need to look at permanent costings and spell costs but I hope to have point costings for all the commons up at some point over the next month of so.