AdmiralMemo wrote:Elite Arcanist + Strionic Resonator
If I cast the Arcanist, his ability triggers. I can then activate the Resonator to duplicate it. This will exile 2 instants from my hand. However, the question comes from the second ability of the Arcanist: Can I choose which instant to cast, or is it a specific one, or is it both somehow?
It is, in fact, both. The Gather rules for
Strionic Resonator mention that
"The source of the copy is the same as the source of the original ability", which means it is your
Elite Arcanist that is effectively exiling both cards. When you later activate the Arcanist's ability it actually applies its actions to each of the exiled cards (Comp. rules 607.3). This means that all exiled cards are copied and you may cast any number of them without paying their mana costs.
However, because you first need to determine the mana cost of the Arcanist's ability you need to look at all of the cards exiled and add their mana costs together to get the value of X. A bit like adding the costs of split cards together, but this time you actually can cast both (or just one, or neither) because they are separate cards.
Kapol wrote:If I use a
Whip of Erebos to bring back an
Ashen Rider, then sac it through one means or another, do I still get the second ability activation from the 'dying' trigger? Or, more likely, do I miss out since it's exiled right away from the whip?
The replacement effect on your
Whip of Erebos is going to exile your
Ashen Rider instead of letting it go to the graveyard, and since "dies" means "is put into a graveyard from the battlefield" it will not trigger off an exile like this.
Edit: Which is more or less what korvys said