OK, I was just concerned about if the spell was grouping the cards (like how Fireball distributes damage) or the player (like Pyrotechnics) and couldn't find a CR reference.

For the purposes of Celestial Toymaker does Hostile Negotiations count as causing "one or more players to guess or to group cards or permanents into a pile this turn"?

Nissa, Who Shakes the World has a triggered mana ability. The she makes is in addition to the mana made by the land. You will end up with after you tap Simic Growth Chamber for mana.

(I know that last part is worded a bit weirdly, it is because stuff like Mana Reflection exists and so technically you are still only tapping the Simic Growth Chamber for , but then the trigger is also adding .)

No.

An easy acronym for what protection stops is DEBT. Something with protection can not be Damaged, Enchanted/equipped, Blocked, or Targeted by a source that it has protection from. Dead of Winter and Bontu's Last Reckoning do none of those things, so protection does not interact with them.

Personally I don't want them to drop the legend rule. I would much rather that they go back to just a few legendaries per set. The recent glut of legendaries is ostensibly for players like me, but I don't like it. I also don't like that every set has to connect into the multiversal adventures of "our heroes" which is, I feel part of the problem. When the antagonist is a multiversal threat it will be the legendary inhabitants of the realm that rise up to fight it. Not some random White Knight or Bomber Corps.

It is correct that you will not get to assign more damage damage than the creature had power at the beginning of the combat damage step.

Your reasoning, however; is a bit wrong. You assign damage from your attackers and the blocking player(s) assign the damage from their blockers. Then all combat damage is dealt simultaneously. The game will try to then give you priority, which means that SBAs will be checked and triggers put on the stack until there are no more SBAs performed or triggers put on the stack. When the first round of SBAs are checked all of your opponents creatures (without indestructible) that were dealt damage by a source with deathtouch will die, as will the enchanted creature if your opponent dealt enough damage to it to kill it. The ability granted by Eternal Thirst will then trigger and will be put on the stack once an SBA check is completed without any SBA being performed. Then there is a round of priority before each trigger resolves putting counters on the enchanted creature (if it is still alive). As you can see there may not be much actual time between damage assignment and getting the counters. But there is a tremendous amount that has happened in terms of game actions and it is well past damage assignment by the time the counters are added.

510.1. First, the active player announces how each attacking creature assigns its combat damage, then the defending player announces how each blocking creature assigns its combat damage. This turn-based action doesn’t use the stack. A player assigns a creature’s combat damage according to the following rules:...

510.2. Second, all combat damage that’s been assigned is dealt simultaneously. This turn-based action doesn’t use the stack. No player has the chance to cast spells or activate abilities between the time combat damage is assigned and the time it’s dealt.

510.3. Third, the active player gets priority. (See rule 117, “Timing and Priority.”)

I feel like if you have 4 Roaming Thrones and haven't already won something has gone horribly wrong.

Wait, I was wrong. It was specifically triggered abilities that cause Ward to be a trigger. Triggered abilities don't have a cost associated with putting them on the stack. There is no way to make something with no cost "cost more" and so they have to counter it if the payment isn't made instead of imposing an additional cost.

It definitely isn't about having non mana payments, since they already have Terror of the Peaks which is formatted in the way you suggest.

The large difference made because of it being "counter unless you pay" instead of a static ability is that it allows other ways of getting around the ward besides paying the mana. I don't know if this was intended, but WotC is obviously aware of this because Long Goodbye was in the same set as Disguise. Benevolent Geist  ^Flip, Boseiju, Who Shelters All, and Abrupt Decay also provide counter play to Ward. I can't provide you with a "why" since I have no inside information, but the most likely explanation IMO is that it was in fact intended that "can't be countered" can be used to counteract Ward.

Correct. The way I most often saw it working with her was to cast an instant after attacking. She is also notorious for baiting targeted removal and then casting an instant to untap her.

Pristine Angel only has protection when untapped so, assuming she doesn't have vigilance, attacking will cause her to tap and she will no longer have protection from all colors and artifacts.