There is normaly only one combat phase per turn, where attacking creatures are declared once, during the declare attackers step. Some effects can create additional combat phases, but there doesn't seem to be something like that involved here. So if your fiance casts a creature after attackers have been declared, that creature won't be able to attack this combat or later this turn. Do note that some effects like ninjutsu can put creatures on the battlefield attacking after attackers have been declared; again, there doesn't seem to be something like that involved, but I can't be sure since you're not naming any of the cards involved.
Once an attacking creature is blocked, barring very specific effects, it remains blocked and the creatures blocking it can't be changed for other ones for the remainder of the combat phase (to be clear, you don't choose blockers, the defending player does). And unless the attacking creature has trample or some other specific ability, it won't be able to assign damage to anything but the creatures blocking it. With double strike, if all blockers are destroyed during the first combat damage step, no damage will be assigned or dealt during the second, "normal" combat damage step. If the double striker also has trample, however, all of the "second strike" will be assigned to the defending player, planeswalker or battle that's being attacked.
You will untap Combat Celebrant, but it specifies that you can only exert it if you haven't exerted it this turn, so you can't exert it again this turn.
Can I ask a question related to this thread? Or should I start my own thread?
It's usually preferable to start new threads in order to keep each of them short and focused and not bump an older thread up from its original timestamp, but here, given the general nature of the initial question, and the fact that the thread is recent, it's ok, go ahead.
Well, apparently my entire pod has been playing Drafna wrong this whole time so thanks for clearing that up. Don't know how we missed the artifact "spell" on there, but for any other copy effect would it be the original or the 3/3 version?
The 3/3 golem artifact version. That's because that modification to the original's characteristics is part of Nexus of Becoming's copy effect, as denoted by the wording "except it's a...". Those characteristics become the copiable characteristics of the token, which is created that way and doesn't have the original's power and toughnesss "underneath". Your friend is right that changes from various effects aren't usually copiable, but an exception is changes from other copy effects, those are.
All Elf Warrior tokens enter at the same time, but they still all trigger Ivy Lane Denizen separately. For each trigger, you can target any creature on the battlefield to get a +1/+1 counter, be it one of the tokens that were just created or anything else. You can put one counter on each token or put several counters on the same target, that's up to you.
Savra has two separate triggered abilities and sacrificing a creature that's both black and green will trigger them both.
Keep in mind that Savra herself doesn't give you any way to sacrifice creatures, though: she only has triggered abilities that trigger when you happen to sacrifice a creature through some external cost or effect. An activated ability that allows you to sacrifice a creature as a cost will be worded something like "Sacrifice a creature: [effect]". Just making sure since your post didn't make it clear that you knew that; distinguishing activated abilities and triggered abilities is important, they function very differently.
If an effect causes each player to mill cards, does Scorchbeast create zombies base on the total number of nonland cards milled, or does it only look at one player?
Because of the way Sreeching Scorchbeast's ability is worded, if all players mill at the same time (which is what happens if an effect says "each player mills [number] cards", it indeed sees one trigger event and it looks at all players to determine the number of tokens.
Let’s say that counterpoint targets a creature i’m trying to cast and i give it hexproof, does the second half of counterpoint still resolve?
Hexproof is an ability that can only be given to permanents or players, and a creature spell on the stack is not a permanent. A spell that says "target creature gains hexproof" can only target a creature permanent already on the battlefield, so it can't be used to protect a creature spell on the stack from a counterspell-type card like Counterpoint. To my knowledge, no card currently exists that makes it so spells you control can't be the target of spells controlled by opponents, but such a card would be possible in theory, and if it would be applied in response to Counterpoint here, Counterpoint would fizzle, so it would again not resolve and none of its effects would happen, because that's what happens when of all of a spell or ability's targets are illegal at the time of resolution.
As bonus info, some cards make it so that spells you control can't be countered, but the interaction with Counterpoint would be different. Such effects don't stop a counterspell from resolving and they don't make the targeted spell an illegal target for the counterspell, they just make it so that the counter action fails to do anything. So here, the second part of Counterpoint would work even if the spell it targets can't be countered.
Let’s say that counterpoint targets a creature i’m trying to cast and i give it hexproof, does the second half of counterpoint still resolve?
Hexproof on a card in a graveyard does not apply. It doesn't do anything. The counterpoint can resolve in that construction.
I think the OP meant giving hexproof to the spell targeted by Counterpoint rather than giving hexproof to the card in the graveyard, but in addition to what you said, we can also point out that making cards in the graveyard untargetable wouldn't do anything as Counterpoint doesn't target the graveyard card that it would allow its controller to cast.
No, if Negate resolves targeting Counterpoint, Counterpoint is countered, it doesn't get to resolve and none of its effects happen. The card that Counterpoint would allow its controller to cast from their graveyard is not even officially chosen unless and until Counterpoint resolves.
If a land gets cloaked, can i uncloak it any other way by using Kaust, eyes of the glade for example
Yes, effects like Kaust's will be able to turn a face-down creature face up as long as it's a permanent card, including if it's a land. To note, if it was attacking or blocking (necessarily attacking, for Kaust in particular), it's removed from combat as soon as it stops being a creature. If it's an instant or sorcery card, it's revealed, but it's not turned face up, it remains a face-down creature with base p/t 2/2 and it stays in combat if it was attacking or blocking.
On a related note, can my opponent destroys the Eidolon before Three Dog has a chance to sacrifice it? Since saccing the Eidolon isn't part of the "payment" for the trigger.
No aura is sacrificed to Three Dog's attack trigger until that trigger resolves. Triggered abilities that include costs do not have their controller pay those costs until the ability resolves. So your opponent can wait until Three Dog is declared as an attacker and his attack trigger is on the stack to remove an aura, preventing you from sacrificing and copying it. On the flip side, if there's still another aura on Three Dog, you can sacrifice it instead when the trigger resolves. Since the choice and the sacrifice aren't made until resolution, they can't be responded to and the ability happens in full from that point.
Barring things like first strike or double strike, all of the combat damage is dealt at the same time and replaced at the same time by the Alchemist, even if it's from mutliple sources, so it'll be only one Mothman trigger.
Undying doesn't trigger as a result, because the game looks at the Wolf as it last existed on the battlefield to determine whether it should trigger. Since SBAs are all carried out at the same time, at one point in time, the Wolf has a +1/+1 counter on it, and at the very next point in time, it's no longer on the battlefield. So since it had a +1/+1 counter as it last existed, Undying doesn't trigger.
Not at any point, no. When your commander moves to your graveyard, you get one occasion to put it in the command zone immediately as a state-based action, but if you opt not to do it at that point and leave your commander there, it stays there until some cost or effect tries to move it from the graveyard. If an effect exiles it from your graveyard, for example, then you'll get an occasion to put it in the command zone from exile, and if something tries to put it in your library, you can put it in the command zone instead as a replacement effect. But you can't just put it in the command zone at will.
Keep in mind that Savra herself doesn't give you any way to sacrifice creatures, though: she only has triggered abilities that trigger when you happen to sacrifice a creature through some external cost or effect. An activated ability that allows you to sacrifice a creature as a cost will be worded something like "Sacrifice a creature: [effect]". Just making sure since your post didn't make it clear that you knew that; distinguishing activated abilities and triggered abilities is important, they function very differently.
As bonus info, some cards make it so that spells you control can't be countered, but the interaction with Counterpoint would be different. Such effects don't stop a counterspell from resolving and they don't make the targeted spell an illegal target for the counterspell, they just make it so that the counter action fails to do anything. So here, the second part of Counterpoint would work even if the spell it targets can't be countered.
EDIT:
I think the OP meant giving hexproof to the spell targeted by Counterpoint rather than giving hexproof to the card in the graveyard, but in addition to what you said, we can also point out that making cards in the graveyard untargetable wouldn't do anything as Counterpoint doesn't target the graveyard card that it would allow its controller to cast.