Not A Bug Triarch Praetorian - no trigger

[Drakos]

I used the trigger from "Anrakyr the Traveller" to play "Triarch Praetorian" from the graveyard for life instead of mana. Although the card states "When Triarch Praetorian enters the battlefield from a graveyard, you draw two cards and you lose 2 life.", I did not get the trigger to draw cards.

 

[owlandcrab]

This is not a bug.

As part of the process of casting a spell, you move the object from its current zone to the stack. As far as the game is concerned, your Triarch Praetorian entered the battlefield from the stack, not the graveyard.

CR601.2. To cast a spell is to take it from where it is (usually the hand), put it on the stack, and pay its costs, so that it will eventually resolve and have its effect. Casting a spell includes proposal of the spell (rules 601.2a-d) and determination and payment of costs (rules 601.2f-h). [...]​