Game mechanic by which players attempt to figure out what is wrong with other players if their ailment is not apparent. Characters who can Heal may use Diagnose to determine how much healing the target may need. Not everything can be detected by Diagnose. From the Accelerant core rules:
"This effect is used to determine if the recipient is inflicted with a specific effect, trait, or game condition. Skills with the Diagnose effect allow you to use Diagnose to determine the presence of specific effects or traits with the exception of Imbue or Inflict effects. A skill might also allow you to use Diagnose to determine if the recipient is currently Stable, Unstable, Dead, or Damaged. To use Diagnose, touch the recipient with a packet and say "Diagnose" followed by an effect, trait or game condition. The recipient says "Yes" if they are afflicted with the named effect or an effect with the named trait, or if they suffer the game condition. Otherwise they say "No.""
"Travis, for example, is lying on the ground unstable and has been inflicted by a Slow by Disease and a Paralyze by Magic. Another player leans over, touches him with a packet and says "Diagnose Stable." Travis says "No." She says "Diagnose Unstable" and Travis says "Yes." She uses a Heal effect on Travis but he still doesn't move. Puzzled, she says "Diagnose Stun." Travis says "No." She says "Diagnose Paralyze." Travis says "Yes." She has the ability to Cure Poison, so she says "Diagnose Poison." Travis says "No." She decides to wait until the Paralyze wears off."
"If someone uses "Diagnose Damage" on you, you may choose, for the sake of expediency, to include in your reply the current number of Vitality points that have been removed by Damage. If, for example, you have taken two damage that has not been healed and someone uses "Diagnose Damage" on you, you may reply with a simple "Yes" or you may reply with a "Yes, two." The choice of how to respond is up to you."