Same as it has always been - Psion matching 4 skulls when entangled does not trigger the drain. There is no trait flash. Psion is clearly not stunned here and he has all three traits. Recorded this five minutes ago on the current version of the game.
As I said, status application traits work differently. Psion’s is the only skull trait that cares about attack score - status applications care about damage is dealt from skulls (therefore won’t trigger past barrier, won’t trigger through dodge, and will trigger on match 4+ with 0 effective attack) and the other proc types don’t care what your attack score is or whether you dealt damage (they will trigger regardless before damage is even rolled, then interact with dodge or barrier depending on the type used - eg., a Bullseye from a single skull match will be blocked by barrier and should be able to be dodged.) Then we have the two “buff” types - they will trigger either while the user is in the first spot and matches skulls, or while the user is in any spot and skulls are matched (eg., Courage vs Draakulis), but these are usually differentiated but still ambiguous (Draakulis/Warlord “when I deal skull damage” does not require actual damage to be dealt but requires them to be in front vs “on skull gem matches” trait from Courage/Maw triggers with them in any position.)
This is something I keep bringing up - traits and spells really at least need description passes so you can easily tell what they do.