You move forward, Gran seeming sure of where she is going, not towards a cave but there is a particularly thick group of trees and bushes ahead.
And then...
Snap. A large twig breaks under Gran's foot, and she swears.
There's an alien sound from up ahead, like a bear's growl but not quite. It's not something you've ever heard before, but you can't mistake the ominous silence that follows in the forest around you. With those high perception rolls you hear clearly the sound of something stirring, perhaps getting up from its rest, about sixty feet ahead of you.
Roll initiative.
(Sorry about the stealth rolls. The high perception gets you clear warning and essentially a round's head start if you want to prepare something).
(DM, by prepare something, do you mean we can Ready an action, like an attack? Or just in terms of flavour, we can draw our weapons and attempt to not soil ourselves in fear?)
There is a massive owlbear that has just emerged from the thick bunch of trees and is clearly about to charge you. It is fifty feet away at the moment.
Round One Gran Magnum Silent Owlbear
Hold your ground, and get ready, shouts Gran. She has her fists ready to strike, and takes the dodge action.
Silent draws his blade and stills his mind, using his bonus action to manifest an Echo 15 ft. towards the owlbear. He then commands it (no action needed) to sprint 15ft. closer to the owlbear, standing right beside Magnum on his left.
The Echo will now make Silent's attack, throwing a javelin at the owlbear.
This post has potentially manipulated dice roll results.
The owlbear roars as the javelin and the missiles hit, blasting it and piercing it, and it turns in fury. It rises on its hind legs and lunges forward and down, its beak slashing towards Silent's Echo:
Attack: 25 Damage: 15
There ought to be a pop as the Echo disappears, but there isn't; it's just gone.
The owlbear turns and charges the nearest target, Magnum. This time as it stops, the claws flash through the air:
Attack: 9 Damage: 14
There are no birds nearby; they are hiding or have fled. But the clang of claw on metal is so striking, almost like a bell being sounded, than a hundred feet in all directions birds take flight in startlement.
Stealth - 16
Perception - 18
Auspex's Perception - 19
Stealth 5
Perception 13
(OOC: Not bad for two very jangly people.)
Gran's Stealth 16
Oh dear.
You move forward, Gran seeming sure of where she is going, not towards a cave but there is a particularly thick group of trees and bushes ahead.
And then...
Snap. A large twig breaks under Gran's foot, and she swears.
There's an alien sound from up ahead, like a bear's growl but not quite. It's not something you've ever heard before, but you can't mistake the ominous silence that follows in the forest around you. With those high perception rolls you hear clearly the sound of something stirring, perhaps getting up from its rest, about sixty feet ahead of you.
Roll initiative.
(Sorry about the stealth rolls. The high perception gets you clear warning and essentially a round's head start if you want to prepare something).
Magnum abandons his rope as they’ve lost the element of surprise. He activates his Defensive Field for 3 hp.
Initiative - 12
(DM, by prepare something, do you mean we can Ready an action, like an attack? Or just in terms of flavour, we can draw our weapons and attempt to not soil ourselves in fear?)
Initiative - 7
(OOC: If we get a full surprise round Magnum would run up and punch it in the face.)
8 16
There is a massive owlbear that has just emerged from the thick bunch of trees and is clearly about to charge you. It is fifty feet away at the moment.

Round One
Gran
Magnum
Silent
Owlbear
Hold your ground, and get ready, shouts Gran. She has her fists ready to strike, and takes the dodge action.
Magnum is up.
Magnum rushes forward thirty feet to shorten the gap between them, raises his right hand and fires three Magic Missiles at the owlbear's face.
Damage - 12
Silent draws his blade and stills his mind, using his bonus action to manifest an Echo 15 ft. towards the owlbear. He then commands it (no action needed) to sprint 15ft. closer to the owlbear, standing right beside Magnum on his left.
The Echo will now make Silent's attack, throwing a javelin at the owlbear.
Attack: 19 Damage: 8
The owlbear roars as the javelin and the missiles hit, blasting it and piercing it, and it turns in fury. It rises on its hind legs and lunges forward and down, its beak slashing towards Silent's Echo:
Attack: 25 Damage: 15
There ought to be a pop as the Echo disappears, but there isn't; it's just gone.
The owlbear turns and charges the nearest target, Magnum. This time as it stops, the claws flash through the air:
Attack: 9 Damage: 14
There are no birds nearby; they are hiding or have fled. But the clang of claw on metal is so striking, almost like a bell being sounded, than a hundred feet in all directions birds take flight in startlement.
Round Two
Gran
Magnum
Silent
Owlbear
Boys, says Gran, rolling her eyes. And she runs up to flank the creature with Magnum as she punches the creature:
Attack: 19 Damage: 3
Attack: 17 Damage: 2
You can see she's quick, accurate, but doesn't pack a lot of punch in her, um, punches.
Magnum is up. You are in melee with the owlbear, flanking Gran.
Magnum brings his Thunder Gauntlet down on the owlbear's beak.
Attack: 14 Damage: 9
(OOC: The owlbear has disadvantage attacking anyone other than Magnum.)
Silent sprints thirty feet towards the fray, swinging his sword in a wide arc at the owlbear's flank.
Attack 24 Damage: 12
Reeling back from the strike, he will then use his bonus action to manifest an Echo 15 ft. above the owlbear, where it is now floating.
(OOC: I didn't know if Silent would get advantage from the owlbear being flanked by two other allies, so I just made a straight roll)
Silent would get advantage from Gran's flanking, given that the owlbear is such a large creature. Feel free to make a second roll for Silent's attack.
(Nice!)
Attack 22
Silent's attack hits, of course. :)
The owlbear is looking very wounded as it strikes at Silent, but the ringing from Magnum's attack seems to have affected it:
Attack: 11 Damage: 10
Attack: 12 Damage: 7
Neither attack hits.
Nearly there lads. Gran goes in with the punches:
Attack: 24 Damage: 2
Attack: 22 Damage: 1
The owlbear is on its last legs. Magnum, you're up.
Magnum sticks close to the owlbear and launches another Thunder Gauntlet at its head.
Attack: 19 Damage: Unable to parse dice roll.