OK,it seems that any spell with a variable casting cost -- one with an (X) in the cost (Fireball, Strength of the Tajaru, ...) -- will not be able to be cast, however, a specific cost spell -- Lightning Bolt, Flensermite, White Knight, ... ) should arrive on the battlefield. And remember, this applies only to those cards that are 'exiled' due to the Omen Machine's ability, not to the cards in a player's hand. IMHO.
Posted By:
StephenF
(5/7/2011 4:24:21 PM)
NOTE: you may have to wait for the errata. "if able" means that only lands, instants and flash can be played as players are still in their Draw phase. Creatures, sorceries, artifacts, enchantments and planswalkers may not be a valid play in this phase.
Posted By:
estranger2000
(5/7/2011 5:28:47 PM)
@estranger2000
The "if able" is only restricting you from casting the card if there's an additional cost you can't pay (eg. "as an additional cost, sacrifice a creature" and you don't have one), if there are no legal targets for it (eg. "destroy target artifact or enchantment" and there are none on the battlefield), or if the card has specific timing requirements (eg. "cast this spell only during combat").
I don't expect the errata/rulings for this to be very different from those for Wild Evocation.
Posted By:
nemokara
(5/8/2011 8:12:50 AM)
A Timmy gets excited and puts it into his giant creatures deck. A Johnny wets himself as he has finally found another card for his Baneful Omen library manipulation deck. A Spike gets angry and throws this at the fan because it costs 
and isn't a Primeval Titan. A lone Sensei's Divining Top curses Johnny for squandering its potential with a glorified Howling Mine
I love this card 4.5/5
Posted By:
Superllama12
(9/11/2012 4:53:59 PM)
Reality ripple and mnemonic wall will net you turns where YOU can draw cards... cavern harpy will let you abuse the walls...what else?
Teferi's Curse-- flip flops the omen machine in and out of play...
Vision charm can be used just like reality ripple... Looks like blue just gained a major 'slow-opponents-down' machine. yay.
Posted By:
Tetsu_tora
(4/29/2011 3:36:45 PM)
im rebuilding my arcum dagsson edh right now, just gonna have this and lots of huge stuff lolololol. srsly wizards, you made the card name...
Posted By:
shawnr3150
(5/3/2011 6:57:23 AM)
Eldrazi decks really like this I assume.
Posted By:
Sironos
(5/3/2011 2:54:21 PM)
@ OneFlame
with omen machine in play players can never draw cards. Instead during the draw step they will exile the top card of their library. weather its a sorcery, creature, or insant doesnt matter. the only restriction is if a card says it can only be cast at a certain time. Also you dont draw the card rather you cast it from exile just like suspend.
So Player A plays omen machine. and ends turn. Player B exiles Llanowar Elves. He then casts it putting it onto the battlefied. He then continues his turn as normal. Player A's turn he exiles Aleatory. since it can only be cast during combat it stays exiled.
Posted By:
Urukabaar
(5/15/2011 8:23:18 PM)
"Players can't draw cards."
Well now. That's a sentence I like to start off reading in a text box. Could be fun with Goblin Welder.
Posted By:
Kryptnyt
(4/29/2011 5:46:29 PM)
I'm really biased in rating this card, because I recently built a stack for Chaos Magic, and this is perfect for it. I wouldn't put it in a normal constructed deck, but with Chaos Magic, players getting to cast cards for free, but being unable to choose when to do so, is the type of crazy I look for on a card that goes in the stack. And in Chaos Magic all you need is to have this on the top of the Chaos Deck and be put into play; the {6} doesn't matter at all.
Constructed or limited? I wouldn't touch it. But for Chaos Magic it's absolutely perfect.
Posted By:
sarroth
(5/3/2011 8:57:36 AM)