As Shao already said, Nascent Flash has a 6s duration, that's an uptime of 24%.

In a few Media Tour videos, I've seen it healing the WAR for about 50% of dmg dealt. That means WAR can heal MT with a quarter of thier physical attacks.
Quote Originally Posted by Izsha View Post
You get 3 gcds at best [...]
and max. 2 AA, as WAR AA delay is higher than 3s. It might only one AA, plus 2 GCDs at worst. Healing is a little unrealable.

On PLD mitigation... your uptime is wrong. Oath Gauge increases everytime an AA lands. GLD/PLD weapons have an AA delay of 2.24, each generating 5 Oath Gauge points. That means, every 22.4s you gain 50 Gauge - except on downtime. As long as PLD has 100% uptime on AAs, Intervention can have an uptime of 26.8%. But there will most likely be mechanics, PLD will need to disengage. So I would say Intervention uptime is about 25%.

Someone on this forum has determined that DRK will generate roughly 9k MP/min. If DRK prioritises TBN before Edge/Flood of Shadow (for Darkside) they can use TBN 3 times per minute. So uptime goes up to 35%, maybe higher or lower depending on player skill/usage of Blood weapon and Delirium.