Deathbird Usurper

[jackalopespam]

Deathbird
While Deathbird is active, when you KO an opposing character die with 3D or greater, deal 3 damage to your opponent.

Anti-Monitor
When Anti-Monitor attacks, you may KO any number of your character dice. For each that you do, your opponent KOs one of their character dice.

Deathbird's ability is activated when I KO an opposing character die. When Anti-Monitor Attacks, if I KO 1 die my opponent then chooses to KO one of their own dice. Would this count as a triggering Deathbird's ability since it was my Anti-Monitor that caused the KO? Or since the card text says "your opponent KOs one of their own dice." would this count as them KO'ing dice for game purposes.

Truce
KO up to two character dice you control. For each character die you KO this way, your opponent must KO a character die they control.

Truce has a similar wording in that "your opponent must KO a character die they control." If I play Truce, does that count as me KO'ing opposing characters or does the opponent take credit?

[dmrulesteam]

The over-arching question here is: what caused your opponent KO their dice?

In both Anti-Monitor and Truce’s abilities, the cause of your opponent KO’ing their dice was in response to you paying a cost (the KO’ing of your dice) to initiate those abilities, i.e. your action caused an opposing die to be KO’d.

Therefore, Deathbird would trigger for each die they KO’d that was 3D or greater.