In a nutshell
- All of these mechanics change the process of casting a spell by letting you do something (tap a creature, exile a card in your graveyard, tap an artifact) rather than paying for mana in its cost. The only difference in how these abilities work is what they let you do instead of paying the mana. Questions involving one ability can be adapted to apply to the other two and the answers are the same.
- Convoke is the only one that allows you to pay for colored mana symbols this way. The others only can act on the generic mana portion. None of these abilities can be used to pay for colorless mana symbols.
- Because these are alternative ways to pay mana, they act on the final cost, after it’s locked in and after the player has activated mana abilities. This has the following consequences:
- If an additional cost is imposed, such as by Sphere of Resistance, that can be paid for with the ability. If a cost-reducing effect, such as Helm of Awakening is applicable, these abilities take that into account too. These abilities function after even Trinisphere has vetted the mana cost, so it won’t see you actually paying 1 mana to cast Treasure Cruise. Just a normal 8 mana sorcery, which it has no reason to care about.
- These abilities apply as you’re paying the cost. This is after the player has the chance to activate mana abilities, so you can’t sacrifice an artifact to Krark-Clan Ironworks after tapping it for improvise.
- These abilities can be used to help cast the spell even if it’s being cast for an alternate cost.
- It’s not possible to “overdelve” or “overtap.” You can’t exile extra cards or tap extra creatures or artifacts.
- The definitions of convoke and improvise in the CR have the word “tap” spelled out rather than using the tap symbol. What this means is that it’s possible to tap creatures for convoke (and artifact creatures for improvise) the turn they entered the battlefield.
A: Having Trinisphere in play doesn’t affect Treasure Cruise at all. First the game will determine the total cost to cast Treasure Cruise starting with the mana cost then taking into account any cost modifiers. Since it costs 7U, Trinisphere doesn’t interact with this at all. Later, when it’s time to actually pay this cost, you can exile cards from your graveyard rather than paying mana. Even if you exile 7 cards and pay only U, Trinisphere won’t try to increase this because it happens after the time Trinisphere is taken into account.
A: Yes. Convoke acts on the total cost of the spell you’re casting. This is the mana cost as affected by applicable cost changing effects. The game doesn’t have any way to separate the mana in the total cost based on whether it’s from the original mana cost or was added during this process, so you can tap to pay for convoke just fine.
A: Yes. Convoke doesn’t care about what mana was spent to cast a creature, just that it is the appropriate color. Tapping Zealous Guardian can pay for a white, blue, or generic mana in the cost of a spell with convoke.
A: Yes. Since convoke and improvise aren’t alternate costs, there’s no barrier to combining them. Having convoke gives you a choice between paying mana and tapping a creature when casting the spell. Adding improvise just adds an additional choice for the generic mana.
Note: If you tap an artifact creature, that will only count for one, since you can’t tap the same thing two times to use it with two different abilities.
A: No. Tapping an artifact to improvise can only cover generic mana; it can’t be used to pay any mana that has a color requirement attached to it, including colorless mana.
Note: Convoke works the same way, but with the additional caveat that colored mana can also be paid by tapping a creature of the appropriate color. Unfortunately, colorless isn’t a color, so it’s not possible to cover this mana by tapping a creature either.
Note: Hybrid mana symbols function by giving the player a choice of what kind of mana to pay, and this choice is made before the cost is paid. That means that, for example monocolor hybrid symbols like those used on Spectral Procession are able to be paid with improvise by choosing to pay the colorless half.
A: No. These abilities act on the “total cost” to cast the spell, not the mana cost. This is why you can use them when paying an alternate cost. As a consequence, you can’t use abilities like convoke anytime you’re paying the card’s mana cost, just when you’re casting them.
A: No. The total cost to cast a spell is determined before that cost is paid, and improvise taps the artifacts as part of paying the cost. Trinisphere looks at the total cost of the spell, which means its effect applies before you get a chance to tap it with improvise.
A: Yes. Flashback gives the spell an alternate cost that lets you play the spell from an unusual zone. Since you’re using an alternate cost to cast the spell, you can’t combine this with other alternate costs. For example, you can’t flashback a Force of Will by exiling a card and paying 1 life. Delve isn’t an alternate cost, though. It’s an alternative way to pay the mana in a spell’s cost, similar to paying 2 life in lieu of paying Phyrexian mana or choosing which mana to pay for a hybrid mana symbol. Because of this distinction, you can use Delve to pay for mana in an alternate cost.
Note: You can’t exile Treasure Cruise itself in this process because at the time delve takes effect, Treasure Cruise will be on the stack.