Écho d'enseignement (Didact Echo)
Écho d'enseignement 

Descente 4 — L'Écho d'enseignement a le vol tant qu'il y a au moins quatre cartes de permanent dans votre cimetière.
Texte de règles (Oracle, anglais)
Descend 4 — This creature has flying as long as there are four or more permanent cards in your graveyard.
Le peuple de l'Empire du Soleil respecte ses ancêtres. Les Oltèques vont plus loin : ils communient avec les esprits de leurs anciens les plus estimés après leur mort.
Légalité
Précisions de règles (en anglais)
2023-11-10
Cards with the ability word "descend N" have abilities that care if you have at least N permanent cards in your graveyard.
2023-11-10
Some descend triggered abilities include intervening "if" clauses (i.e. "if you have [four or eight] permanent cards in your graveyard" in the middle of the ability). Each of these abilities checks your graveyard at the moment it would trigger to see if it does. If you don't have the required number of permanent cards in your graveyard at that time, the ability doesn't trigger at all. If it does trigger, it will check again as it tries to resolve. If you don't have the required number of permanent cards in your graveyard at that time, the ability won't resolve and none of its effects will happen.