MTG : Sidisi, Undead Vizier : Exploit

Sidisi, Undead Vizier released in “Dragons of Tarkir” will serve us an example for a brief yet contentful tale of Exploit.

Sidisi, Undead Vizier is a legendary creature with two creature types: Zombie and Snake. Two legendary Sidisi cards exist in Magic: Sidisi, Undead Vizier and Sidisi, Brood Tyrant. Since they have different full English names, you may control one of each at the same time. And since they are legal in the same formats at the same time, you may not write “Sidisi” in your tournament decklist for either — this will obviously not define the card unambiguously.

Sidisi's first ability, Deathtouch is well known to us. Deep down, the three things of interest are:

It doesn’t matter if the damage from a source with Deathtouch is combat damage or not, the result will be the same.
In order to figure out the consequences of damage from a source with Deathtouch, we use the LKI — last known information, which is pretty unusual for a static ability.
Deathtouch has no effect on non-creature Planeswalkers and, obviously, players. It affects only creatures taking damage.

Sidisi’s second and third ability bring us to the main topic of this article.

Exploit

702.109a. Exploit is a triggered ability. “Exploit” means “When this creature enters the battlefield, you may sacrifice a creature.”

“When this creature enters the battlefield, you may sacrifice a creature.”

When is a trigger signal word.
this creature enters the battlefield is the triggering event, the trigger goes off when the creature hits the field. It is irrelevant how exactly this happens. You do not need to actually cast the creature spell, it may appear on the battlefield in any other way, for instance, through the effect of Stolen Identity.
you may sacrifice a creature is the effect of the ability. In order to receive it, you would need to place the trigger on the stack and then resolve it.

You add {3BB}, reveal Sidisi and ask the opponent: “May I?”

The opponent wonders: “What are you sacking?”

— Teh bear.

— Then no, — reveals Cancel.

— Judge!

A judge will come by and explain that when the question about the object of sacrifice is asked, the opponent is considered to have passed not only to Sidisi being cast, but also to her trigger. So he can neither counter Sidisi, nor do anything with the bear at this point.

You cast Sidisi, it enters the battlefield and you ask your opponent: “May I sacrifice?”

The opponent asks: “Whatcha sacking?”

— Guess what! Teh bear!

— Hell no, — the cunning opponent responds, — Doom Blade teh bear.

— Ju-udge!

The judge comes by and explains that while the Exploit trigger is resolving, the CO doesn’t have priority, so he cannot cast Doom Blade.

However, had he said “Doom Blade teh bear!” as response to your “May I sacrifice?”, Doom Blade would have gone onto the stack above Exploit trigger, and resolve and resolved first. By the time that trigger would have resolved, the Grizzly wouldn’t be there, so maybe you would choose to sacrifice another creature. Or maybe you would not bother sacrificing anything. But since he expresses interest in your choice, it means he has agreed to the trigger and is currently watching it resolve.

The Exploit trigger doesn’t target, you decide whether to sacrifice a creature, and which creature exactly, as it resolves. You may sacrifice the creature with exploit itself, if it is still on the battlefield and, most importantly, still under your control. If the creature with Exploit has been “borrowed” by your opponent before the trigger started resolving, you cannot sacrifice it. However, since you still control the trigger, you may sacrifice another creature you control (if you need to get rid of it for some reason), but Sidisi’s other trigger will be controlled by your opponent, and he will benefit from its effect (look for a card in his own library, obviously).

Exploit doesn't target, so you may sacrifice any creature you control, even one with Protection and/or Shroud.

To sacrifice is not to destroy, so you may sacrifice a creature with Indestructible.

And to conclude with the most obvious, you may only sacrifice one creature per exploit trigger, not five lousy saprolings! This is indicated by the article “a” in front of “creature”.

702.109b. A creature with exploit “exploits” a creature when the controller of the exploit ability sacrifices a creature as that ability resolves.

“When Sidisi, Undead Vizier exploits a creature, you may search your library for a card, put it into your hand, then shuffle your library.”

When is the trigger signal word again.
Sidisi, Undead Vizier exploits a creature is the triggering event, the trigger goes off when we sacrifice this ability at the point when the ability resolves (see the rule just above). If you sacrifice Sidisi herself, the trigger still goes off, and exists independently from its source thereupon.
you may search your library for a card, put it into your hand, then shuffle your library is the effect allowing you to search your library for any one card without revealing it, put it into your hand, then shuffle your library. If you decide not to look for the card, you won’t shuffle.

⇑ By the way, the same peculiar treat is inherent to Lifelink.

Translated by Witas Spasovski

Sidisi, Undead Vizier

Oracle Text:

Exploit