That's not justice, that's judgement. Justice summons you one of every standard item (A penny, a heart (or half heart?) a bomb and a key.) Anyways since I got 25 wins in the beta, I know an absurd amount about the game.
The Devil puts you into max damage mode.
Lovers summons two hears
Temperence summons a heart-to-money machine
Wheel of Fortune summons a roulette wheel
The Magician gives you homing shots
Strength makes you large and gives you +1 max health
Hanged man makes you float
The World shows you the whole map
The Hermit takes you to the shop
Hierophant gives you two blue hearts
The Fool teleports you somewhere random
The Chariot puts you in MAGICAL UNICORN MODE (it's like a star in mario)
Any thing that intrinscially gives you a new ability or life goes away when you leave (notably with devil, strength, hangman), but things that are made are obviously permenant. I think theres one that gives you a devil deal but I can't remember the name.
So other advice
* Don't fuck with pills unless you have a Lucky Foot or a PHD. Those keep you from incurring stat damage from pills. The only other time you'd use a pill is in an emergency. Cain gets a Lucky foot from the get go, meaning if you play him you can suck down every pill relatively. You can still get 'negative' effects, like pooping bombs, but nothing permanent. So unless it's an emergency pill, be sure to use them in a safe place.
* Clear out the entire level in the first for levels. YOu want all the keys and bombs you can get and they're easy stages. Clearing out levels 5 and 6 can be worthwhile, but a bit more risky and keys aren't terribly important in levels 7 and 8. Bombs are a great way to kill mom's heart though, so are worth collecting.
* Secret rooms are a great source of money and extra items and finding them can up your win percentage. As far as I've seen, secret rooms ALWAYS connect to at least 2 rooms and tend to prefer areas with even more connections. If you have extra bombs you can hunt them out safely and systematically. Well, until the later chapters where their are far too many rooms.
* Conserve keys. Generally early on I don't bother going into a shop unless I have either 15 coins (cost of a major item), or a lot of extra keys and 7 coins (the price of an onsale major item).
* It's almost always worth bombing to get to a chest, though opening a locked chest takes more consideration. You want to have at least a key to get the levels item, but a chest is probably more valuable than going into a shop (and often will give you extra keys anyways).
* Beggers are awesome. They have better payoff rates than slots and tend to give you a major item within roughly 10 coins. The items tend ot be maps, compasses, batteries (!!!) or life.
* Compasses and maps make the last two levels much easier. Since they have no items or shops (usually) it's best to just to go straight to the bosses.
* Some rocks are discolored. Bombing them is like opening a chest, only its bias toward blue hearts, bombs and keys. Occasionally it drops a rock, which ups you damage and uppded damage is TOTALLY SWEET.
* Since there's little to use money on in the last two levels, gambling away all your money before the first mom fight is great if you can do it.
* At some point you're going to need to choose between secondary items. I'll give some advice and point out some exceptional items
Unicorn horn: Makes you invulnerable temporarily and makes you do damage by running into enemies. WITH YOUR HORN. Can destroy whole rooms do big chunks of damage to bosses for free. Takes a lot to recharge though and should not be taken over faster, but still great items
Book of Beliel: Pound for pound the best use item in my opinion. Puts you into max damage mode for the duration of an encounter and charges fast.
Book of Shadows: Makes you invulnerable for about 10 seconds and recharges quickly.
Tammy's head: Shoots high damaged shots in all directions. Not very powerful, but recharges on every screen, so you can use it on EVERY encounter.
There are others too, but most of them are unlocks for beating the game several times (Nail, Book of Revelations, Dice...).
Item's like Bob's Rotten Head and Doctor's Remote aren't particularly great, but can be used to hunt for secret rooms without wasting bombs. Every time it fills up, just go test a wall and charge it again.
In terms of character strength, Cain is probably the best until you you get the dice for Isaac (Which is hard). He can suck down pills, does a bunch of damage is fast and only loses one max health and a bit of range. He also gets better drops on average. Isaac (without dice) and Maggie are about equal (though Maggie is probably best for beginning players) and Judas is fun but hard to consistently win with if the game doesn't give you a lo of life-ups.
Any questions?
