Key:PHDOWN
Character:SAM! AKA SAM I AM
Skill(or transformation):AT3 Mastery
How well do you know the source material?(obviously not relevant if it's a transformation):After conflict that induced mass trauma, transformations for a alien could be obtained - with this they would be able to overwhelm their target with power, however they will always be able to tap into this power, through time and proper training they would be able to hold this form without the loss of so much energy mastering the form to fight longer in battle.

Reasoning: After achieving the third transformation sam thought it was very hard for her to master it, she found her self in countless fights where xenop would ask too much of her in order for him to keep up in his potential, however, she was still able to keep up  the most of them , she found her self countlessly retreating in fights, It wasn't untill another life form aquired the same form that she knew what she most do
Consuming the symbiote Tarus- Xenop would be able to devour and gain knowledge from Tarus's symbiote and after he gained the knowledge from consumeing him xenop was able to understand the new transformation - causing him to understand how to manage the energy from both sam and him self creating perfect harmony between each other.
What is the moment: NO IT IS NOT