Fortunately, you discover this rule during a pretty unimportant match, not during a decisive game that might have allowed you to reach rank 21.
As you, I'm still discovering the real meaning of some words and their effects in game.
For example, Birna "applies" a skellige storm on an enemy row, she does not "spawn" it. Which means that skellige storm card is not created, and doest not end in the player graveyard. Therefore, Aglais can't steal this card from the opponent graveyard.
Sometimes, I forget this fatal rule and play a "vanilla" Aglais just after my opponent played Birna.
Hybridizationn : Manticore also creates synergy with ghouls and Ozzrel. Thanks to the manticore, you may have a 17 STR bronze card. Not bad, If you ask me.