Insightful Investigator

Insightful Investigator reads "When you play me, choose an opponent. They reveal their hand. You may pay 2 XP to choose a card from their hand. If you do, they discard that card and draw 1." Here we see the final example, where the ability contains a cost within instructions that does not fall where we would expect it to be for the sequence. This cost within instructions is paid on resolution and not as the base cost of the triggered ability. The ability can be split into "When you play me," and "Choose an opponent. They reveal their hand. You may pay 2 XP to choose a card from their hand. If you do, they discard that card and draw 1." The second part of the ability is all one chain item-it resolves it one go, and cannot be reacted to partway through resolution.

204.3.b. When Costs within Instructions appear in spells, activated abilities, or in later parts of triggered abilities, the cost must be paid to get the effect during resolution of the spell or ability. Example: Bullet Time is a spell that reads "Pay any amount of [A] to deal that much damage to all enemy units at a battlefield." As the spell resolves, its controller pays any amount of [A] as a cost, and deals that much damage to all units at a battlefield as the effect. Example: Ancient Henge is a gear that reads "[Reaction][] [E]: Pay any amount of Energy to Add that much [A]." As the ability resolves, its controller pays any amount of Energy as a cost, and Adds that much [A] as the effect. Example: Insightful Investigator is a unit that reads "When you play me, choose an opponent. They reveal their hand. You may pay 2 XP to choose a card from their hand. If you do, they discard that card and draw 1." As the ability resolves, its controller may pay 2 XP as a cost, and chooses a card from that player's hand as the effect.

383.3.b. If a Triggered Ability contains a cost within instructions at the beginning of the effect or immediately following the "you may" or "they may" that appears as the first part of the effect, that cost is treated as the base cost of the Triggered Ability. Example: Ekko, Recurrent reads "[Deathknell][] Recycle me to ready your runes." In this case, "recycle me to ready your runes" is a cost within instructions that appears at the beginning of the effect of the ability, and thus "recycle me" is taken as the base cost of the triggered ability. Example: Insightful Investigator reads "When you play me, choose an opponent. They reveal their hand. You may pay 2 XP to choose a card from their hand. If you do, they discard that card and draw 1." The "pay 2 XP" is a cost within instructions, but because it does not appear in the first part of the effect, it is not taken as the base cost of the triggered ability. Paying 2 XP is performed on resolution.