You didn't say how many cards are in your opponents' graveyards; I'll call that number n.
Your main phase begins.
You get priority and cast Soul Separator. You pay the cost using 3 obtained in an unspecified manner. Note that you can not choose a target for this spell.
114.1b Aura spells are always targeted. These are the only permanent spells with targets. An Aura’s target is specified by its enchant keyword ability (see rule 702.5, “Enchant”). The target(s) are chosen as the spell is cast; see rule 601.2c. An Aura permanent doesn’t target anything; only the spell is targeted. (An activated or triggered ability of an Aura permanent can also be targeted.)
112.6. Abilities of an instant or sorcery spell usually function only while that object is on the stack. Abilities of all other objects usually function only while that object is on the battlefield. The exceptions are as follows:
(None of the exceptions under rule 112.6 would apply to the Consuming Aberration card in your graveyard.)
You get priority and pass.
Opponent gets priority and passes.
The top object on the stack (the spell cast in step 2) resolves. You put Soul Separator onto the battlefield.
You get priority and activate the ability of Soul Separator. You choose the Consuming Aberration card in your graveyard as the target. You pay the cost by spending 5 obtained in an unspecified way, tapping Soul Separator, and sacrificing Soul Separator.
You get priority and pass.
Opponent gets priority and passes.
The top object on the stack (the ability activated in step 6) resolves. You exile the Consuming Aberration card. You create a token with a name of Consuming Aberration, a mana cost of 3UB, types of Creature - Horror Spirit, abilities "flying" and "Whenever you cast a spell, each opponent reveals cards from the top of his or her library until he or she reveals a land card, then puts those cards into his or her graveyard.", and power/toughness of 1/1. You create a token with a name of Zombie, types of Creature - Zombie, color black, and power/toughness of n/n.
706.9d When applying a copy effect that doesn’t copy a certain characteristic, retains an original value for a certain characteristic, or modifies the final value of a certain characteristic, any characteristic-defining ability (see rule 604.3) of the object being copied that defines that characteristic is not copied. If that characteristic is color, any color indicator (see rule 204) of that object is also not copied.
Example: Quicksilver Gargantuan is a creature that reads, “You may have Quicksilver Gargantuan enter the battlefield as a copy of any creature on the battlefield, except it’s still 7/7.” Quicksilver Gargantuan enters the battlefield as a copy of Tarmogoyf, which has a characteristic-defining ability that defines its power and toughness. Quicksilver Gargantuan does not have that ability. It will be 7/7.
You get priority and ....
Private Mod Note
():
Rollback Post to RevisionRollBack
Why bother with mere rulings when so many answers can be found in the Rules?
One more question, since the n/n changes on the original card, does it change on the newly created Zombie Token (my suspicion is no)
Indeed. It could probably written to copy that power/toughness, in which case the characteristic-defining ability would be copied. But it wasn't, so it just sets that power/toughness at that time. (If the opponent does something during the above process to move cards in or out of the graveyard, the count at step 9 is the one that matters.)
608.2g If an effect requires information from the game (such as the number of creatures on the battlefield), the answer is determined only once, when the effect is applied. If the effect requires information from a specific object, including the source of the ability itself, the effect uses the current information of that object if it’s in the public zone it was expected to be in; if it’s no longer in that zone, or if the effect has moved it from a public zone to a hidden zone, the effect uses the object’s last known information. See rule 112.7a. If an ability states that an object does something, it’s the object as it exists—or as it most recently existed—that does it, not the ability.
Private Mod Note
():
Rollback Post to RevisionRollBack
Why bother with mere rulings when so many answers can be found in the Rules?
Could someone explain what happens if Soul Separator is played with Consuming Aberration as the target?
You didn't say how many cards are in your opponents' graveyards; I'll call that number n.
One more question, since the n/n changes on the original card, does it change on the newly created Zombie Token (my suspicion is no)