Some of us are struggling to understand how newly revealed card “Target Spotter” (Shuri’s hero pack) works…

Firstly, let us state that if a player uses Target Spotter’s ability on a minion that would engage a different player, that minion does not engage that different player, only the player that triggered Target Spotter. This baseline should help clarify its interactions with the following cards.

For events with an ability cost involving discarding and engaging a minion (Squared Off, Defender of the Nine Realms, etc.), the player can attempt to pay the ability cost by discarding cards, then if a minion is found the Target Spotter player can change who the minion engages; if they do, the ability cost of the event is not considered paid, its post-arrow effect fails, and it gets discarded.

Chooser of the Slain is mostly similar in that the search is allowed and Target Spotter can change the minion engagement, resulting in the ability cost being unpaid and the event getting discarded.

Normally, if it’s known the cost can’t be paid, the card can’t be played; but with these events having ability cost relying on uncertain information, they allow for an attempt at payment, and Target Spotter is able to interrupt that process.

For Infiltration, the player that the minion engages is inconsequential to the rest of the card’s ability; the cost can still be paid and the post-arrow effect still has at least one valid target even if the minion engages a different player.

For Face the Past, as long as the minion is “revealed,” the ability cost is considered paid and the post-arrow effect can resolve. The player that “reveals” the minion can be a different player than the one that “engages” it.

For Angela, as long as a minion is put into play as a result of her ability, she will remain in play. Even if Target Spotter changes the minion’s engagement, Angela still put the minion into play.