Two damage.

113.7a Once activated or triggered, an ability exists on the stack independently of its source. Destruction or removal of the source after that time won’t affect the ability. Note that some abilities cause a source to do something (for example, “Prodigal Pyromancer deals 1 damage to any target”) rather than the ability doing anything directly. In these cases, any activated or triggered ability that references information about the source for use while announcing an activated ability or putting a triggered ability on the stack checks that information when the ability is put onto the stack. Otherwise, it will check that information when it resolves. In both instances, if the source is no longer in the zone it’s expected to be in at that time, its last known information is used. The source can still perform the action even though it no longer exists.

First a little information about the site. The Q&A is for rules questions. It's not a big deal and I'm sure a mod will be by at some point to move this thread.

I'm assuming that you mean Modern Horizons 3 and English isn't your first language and the name of the set didn't translate well. The set is scheduled to release June 14 with prerelease events starting June 7 and the official spoilers beginning May 21. The full set contents will slowly be previewed between May 21 and June 7, though I'd guess that previews would be done by June 1, but that last date is supposition.

https://mtg.fandom.com/wiki/Modern_Horizons_3

The most compact Hulk line is going to be Mikaeus, the Unhallowed and Walking Ballista which requires you to add only Protean Hulk and Walking Ballista both of which are decent outside of the combo. The combo does require a sacrifice outlet, and I was having trouble thinking of how to grab one since the combo already uses all 6 CMC of the tutor and I am most familiar with the combo in Abzan where you get Karmic Guide. Luckily DreadKhan supplied the missing piece, if you add in Activated Sleeper you can tutor the Sleeper and Viscera Seer to provide the sacrifice outlet.

Combo I am describing in case you are not familiar with Mike and Ballista. Mikaeus, the Unhallowed gives non-human creatures +1/+1 and undying, so the Ballista enters as a 1/1 and doesn't die. Sacrifice Walking Ballista and it comes back with a +1/+1 counter. Remove the counter from Ballista and deal 1 damage to an opponent. Repeat loop of sacrificing Ballista and removing counter until all opponents are dead.

You are also already running Yawgmoth, Thran Physician, so you can add in a few low cost undying creatures and get that combo with low opportunity cost. Young Wolf and Butcher Ghoul are the easiest to cast ones since they only have a single colored pip. Treacherous Pit-Dweller, Geralf's Messenger, and Strangleroot Geist are perfectly defensible options too, though the pit dweller is more all-in on having a way to sacrifice for value before the trigger to give an opponent control resolves and as such I think isn't a great fit here.

In general you can also up the power level of the deck by adding tutors. The "good" ones you are not running are Worldly Tutor, Grim Tutor, and Vampiric Tutor.

Fetch lands are the best fixing in Magic, so if they are in the budget the answer is always "yes" in multicolor decks.

The rules for deathtouch means that any damage from a source with deathtouch is considered lethal damage. Since Uncle Istvan prevents all damage from creatures, damage from a creature with deathtouch is prevented and he will not die. If you give a spell deathtouch (as Judith, Carnage Connoisseur does) the rules for deathtouch still apply. So he will die to an Electrickery with deathtouch.

I assume it is because of the language in point 3 of the "Prison/other card explanations" section. Not sure though.

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.