MordokĀ“s Obelisk gives every non-Mage creature the Upkeep +1 trait.
I assume that means every creature affected resolves independent. Its a +1 Upkeep on every creature not pay 1 Mana for every creature you have.
(I can pay for one creature then choose another event and then pay for another creature, right?)
You process each creature separately. So you could decide to pay the upkeep on creature A, then to let creatures B and C die, and finally to pay the upkeep on Creature D. Each is an independent decision.
I control "Death Link" enchanted on an enemy's creature.
Is the effect of Death Link on his creature so that my enemy can choose the Order , on my Mage so I can choose or is it one of the rare cases that an timing issue occurs and the initiative decides?
(Lets say he got a Burning/"Ghoul Rot"ed creature with 2 life left.)
With Burns and Ghoul Rot and most any other condition, the creature's controller would decide the order in which to apply them. Death Link is the rare exception where the player with initiative would decide, however.
Example A: I have Regrowth and Ghoul Rot on my creature and it has 2 life left. I can choose to heal 2 points of damage with the regeneration from regrowth before I apply the 2 damage from Ghoul Rot, thereby keeping my creature alive.
Example B: My creature has Regrowth and an opponent's Death Link on it. The creature only has 2 life left. I want to use the Regrowth's regeneration first (thereby keeping the creature alive) but my opponent wants to use his Death Link first (thereby killing the creature). The player with initiative gets to decide.
I cannot choose to activate "Enchantment Transfusion" to rescue my "Death Link" while destroying a creature with it.
(More of an Question to have it in black and white. Because you cannot interrupt an evet to reveal an enchantment.)
If you are destroying the creature with the Death Link, then unfortunately you can not use Enchantment Transfusion to rescue it. If you were destroying the creature with an attack of some kind, then you could reveal Enchantment Transfusion after Step 3: Roll Dice to rescue the Death Link.
The Warlocks ability "Curseweaving" can recycle used Curse Spells.
The Enchantment "Rise Again" has the Curse Trait.
If a creature is destroyed while having "Rise Again" attached, can is Reanimate the creature and still take "Rise Again" back into my Spellbook?
Yes, you can indeed use Rise Again to reanimate the creature AND use Curse Weaving to save the Rise Again spell.