The merged permanent will still be affected by Blind Seer's effect, and therefore it will be blue no matter how you arrange its components. Effects that modify the mutating creature spell will keep modifying the resulting permanent.
Quote from CompRules »
702.139f Any effect that refers to or modifies the mutating creature spell refers to or modifies the mutated permanent it merges with as it resolves.
No, you can't discard it to the top of your library. Mox Diamond requires you to discard a land card. If you apply Library of Leng's replacement effect to the discard, the discarded card won't be revealed and its characteristics will be undefined (even if you choose to show the card to your opponent).
Quote from CompRules »
701.8c If a card is discarded, but an effect causes it to be put into a hidden zone instead of into its owner’s graveyard without being revealed, all values of that card’s characteristics are considered to be undefined. If a card is discarded this way to pay a cost that specifies a characteristic about the discarded card, that cost payment is illegal; the game returns to the moment before the cost was paid (see rule 721, “Handling Illegal Actions”).
EDIT:
Now what if both players are in the same situation, where they both have 7 cards, no permanents in play, and nexus is the last card in the library. Now if both players continue to pass the turn and discard nexus, that is a loop and someone has to break it. Here, I'm not sure who has to...
If no player wants to break the loop in this scenario, the game will end in a draw.
Quote from MTR 4.4 »
Loops may span multiple turns if a game state is not meaningfully changing. Note that drawing cards other than the ones being used to sustain the loop is a meaningful change. If two or more players are involved in maintaining a loop across turns, each player chooses a number of iterations to perform, or announces their intent to continue indefinitely. If all players choose to continue indefinitely, the game is a draw. Otherwise, the game advances through the lowest number of iterations chosen and the player who chose that number receives priority at the point they stop taking an action to sustain the loop.
so how often do judges get these ? just once when they are released or do they get multiple opportunities ?
wanna know if those that are out now is the limit of available cards or if more can be expected to get out
Two new promo cards are released four times a year. Each judge pack contains four cards: two cards from the current wave and two cards from the previous wave. So each card gets two opportunities. For example, the packs from the previous wave contained Teferi's Protection, Lord of Atlantis, Vampiric Tutor and Nin, the Pain Artist. The current promo packs contain Rhystic Study, Food Chain, Teferi's Protection and Lord of Atlantis. The packs from the next wave will likely contain Rhystic Study, Food Chain and two unknown cards.
Your opponent may choose to apply Callous Giant's prevention effect and prevent 3 damage to the Giant. Then Pariah's replacement effect will apply and replace the 3 damage to your opponent with 3 damage to the Giant. Since you won't be able to apply Callous Giant's prevention effect again to the resulting event, the end result will be Punish the Enemy dealing 3 damage to the Giant.
Alternatively, your opponent may choose to apply Pariah first, resulting in 6 damage to the Giant, which the Giant's prevention effect won't be able to prevent.
Your opponent will likely choose the first option and the Giant will live.
Nope, that's not the source.
The source is MagicLleida: https://www.youtube.com/watch?v=Pdk8xiCP78k
Edit: Fixed!
Alternatively, your opponent may choose to apply Pariah first, resulting in 6 damage to the Giant, which the Giant's prevention effect won't be able to prevent.
Your opponent will likely choose the first option and the Giant will live.
It depends. What mode are you choosing for her ETB?
-Weapon: put two +1/+1 counters.
-Fan: gain 4 life.
-Rake: destroy target artifact or enchantment.