The hooded form of the Pater Familias is in view of the doorway. They point a clawed hand at Eoni and cast Suggestion at her. In a rasping voice the Pater suggests she Surrender yourself to the cult. 
DC on the charisma Save is 18

anyone with a passive perception of 14 or higher notices that the clawed hand appears to be backwards (palms on the back of the hands) and it has the faint patterning of a tiger. 

Simisk’s wizened form casts Hold Person on Rollo and then backs away from the door way. 
DC 14 Wisdom Save 

Wisdom save 15

NEVER! Eoni screams at the Pater.

Charisma save 18

Seeing Glodrin brandishing his sword and charging, Draskan casts shield, creating a barrier of magical force around himself

Diomedes goes for the Pater Familias with his mace and then tries to shove him into Simisk with his shield

Attack: 19 Damage: 7

Shove - 3 

9

The mace strikes true but even though it is silvered it seems to have no effect on the Pater. A shove is effective though and sends bit the Pater and Simisk to the ground. The hood falls back as the Pater hits the floor revealing its features. It is feline in appearance with slitted eyes. 
Arcana or Religion check please

Religion - 23 

This is no mortal creature! This is a Raksasha, an emissary of The Lords of Dust, servants of chaos and anathema to all life, including the Traveller. This is no true cult of the Traveller if the head of the family is a Raksasha

Belris will charge up the stairs he will bonus action curse the Pater Before lashing out with his great sword. 
Attack: 29 Damage: 26

Attack: 17 Damage: 15

Seeing the mace do no damage, Leowin draws his short sword and plunges it towards the fallen Raksasha's chest

Short sword of the rogue Attack: 27 Damage: 10

Sneak damage 10

From the shadows 11

The strike hits true wounding the Raksasha 

Seeing the Rakshasa, Eoni turns to the remaining cultists coming up the stairs, Don’t you see? This is all a sham! The Pater serves The Lords of Dust, not The Traveller! He has twisted the words and wisdom of The Traveller to his own end and has manipulated you into doing his bidding! The Traveller teaches that change strengthens people ...use this change for good and help us in ending the Pater’s tyranny!

Persuasion 18

11 4 15 15 20 17 14

6 of the cultists stop their charge towards you and consider your words. The last one blinded by hate continues unabated

Angered by the attack on him, with a mighty roar,  Draskan launches his maul at Glodrin, 

Attack: 12 Damage: 12

Fire Damage 8

Attack: 20 Damage: 14

Fire Damage 7

Both attacks crash into the tiny assassin winding him 

The unconvinced cultist casts fireball at the others only for it to be counter spelled by one of the others. The mage who counterspelled it casts Lightning Bolt for that to be countered by the first one. 

the other 5 lay into the fireballing mage, rapidly filling them full of holes. 
The Paters two bodyguards throw off their cowls, revealing feline countenances, and rush to the Paters’ defense. 
One attacks Belris, one attack Diomedes and Mahrad attacks Leowin 

Belris: Attack: 14 Damage: 5 Attack: 23 Damage: 11 Attack: 16 Damage: 9 Martial prowess: 10

Diomedes: Attack: 13 Damage: 6 Attack: 16 Damage: 12 Attack: 24 Damage: 7 Martial prowess: 12

Leowin: Attack: 24 Damage: 4 Attack: 26 Damage: 11 Sneak attack: 18

Rollo aims at the Raksasha

Attack: 14 Damage: 26

rite 5
Attack: 5 Damage: 26

rite 4