Hjalman uses his action to activate Quivering Palm on Venca (as seconded by @FitzTheRuke
Venca fails DC 18 Constitution save (rolls 4+12 = 16), uses Legendary Resistance to succeed instead. (2 uses left)
Vecna takes 22 necrotic damage (half of 45 rolled).
Hjalman moves west behind pillar.
It is Egar's turn.
Egar's casts Chill Touch as a Ready Action with the trigger that once he Misty Steps (bonus action) to a point he can see Venca it is released.
Egar Misty Steps 30 feet and releases Chill Touch, making a ranged attack and hits! (roll 9 + 11 = 20, hitting Vecna AC's 20 (18 + 2 cover bonus)).
Vecna takes 11 necrotic damage (half of 22 rolled). Until the start of Egar's next turn, Vecna has disadvantage against attacks made against Egar and cannot regain hit points (this denies Vecna's bonus action ability to regain hit points
Vecna uses Fell Rebuke, dealing 9 damage to Egar.
Egar moves east behind pillar, near Leon.
Current Spell Slots: 4 / 2
/ 3 / 3 / 3 / 1 / 2 / - / 1 (Misty Step cast).
It is now Vecna' Turn.
Someone else can run Vecna if they want, but I have to go to work. If no one does, I do Vecna's turn when I get home tonight.