Suppose I have these 3 cards in play. If I activate Aperture and reveal a spell:
Can I play that spell at any time, i.e. play an enchantment during my opponent's turn?
Can I play that spell without paying the extra sphere mana cost?
If I play the spell, will doing so trigger the Nether Void?
Temporal Aperture (2)
Artifact
5, T: Shuffle your library, then reveal the top card. Until end of turn, for as long as that card remains on top of your library, play with the top card of your library revealed and you may play that card without paying its mana cost. (If it has X in its mana cost, X is 0.)
Sphere of Resistance (2)
Artifact
Spells cost (1) more to cast.
Nether Void (3)B
World Enchantment
Whenever a player casts a spell, counter it unless that player pays (3)
- Can I play that spell at any time, i.e. play an enchantment during my opponent's turn?
The rules for when a spell may be cast remains unchanged. For an example of a card that would allow this, see Leyline of Anticipation
- If I play the spell, will doing so trigger the Nether Void?
Yes. Nether Void triggers on any spell cast, regardless of the cost paid (or not paid) to cast it.
- Can I play that spell without paying the extra sphere mana cost?
117.9. Some spells have alternative costs. An alternative cost is a cost listed in a spell's text, or applied to it from another effect, that its controller may pay rather than paying the spell's mana cost. Alternative costs are usually phrased, "You may [action] rather than pay [this object's] mana cost," or "You may cast [this object] without paying its mana cost." Note that some alternative costs are listed in keywords; see rule 702.
117.9d. If an alternative cost is being paid to cast a spell, any additional costs, cost increases, and cost reductions that affect that spell are applied to that alternative cost. (See rule 601.2f.)
601.2f. The player determines the total cost of the spell. Usually this is just the mana cost. Some spells have additional or alternative costs. Some effects may increase or reduce the cost to pay, or may provide other alternative costs. Costs may include paying mana, tapping permanents, sacrificing permanents, discarding cards, and so on. The total cost is the mana cost or alternative cost (as determined in rule 601.2b), plus all additional costs and cost increases, and minus all cost reductions. If multiple cost reductions apply, the player may apply them in any order. If the mana component of the total cost is reduced to nothing by cost reduction effects, it is considered to be {0}. It can't be reduced to less than {0}. Once the total cost is determined, any effects that directly affect the total cost are applied. Then the resulting total cost becomes "locked in." If effects would change the total cost after this time, they have no effect.
tl;dr: Yes, you still have to pay for sphere
Sorry for the triple post.
Thanks for the detailed reply. So, "playing" a spell is considered casting it?
@dr-j "Playing" is a more generic term that is used when the card you're referring to could be a land. By using "play" here, the Temporal Aperture allows you to cast the spell on top or play the land on top.
601.1a. Some effects still refer to "playing" a card. "Playing a card" means playing that card as a land or casting that card as a spell, whichever is appropriate.
