Bree's perception: 15 (her passive is 14.)

Oscsr perception check! 8

(sorry I should have written that better. I just need perception from Bree and Faleon)

Faleon Perception: 13

Without any advanced warning or detection the shadows coalesce into the mastiffs again attacking Faleon and  Bree. With the uninjured one on Faleon.

Faleon bite Attack: 12 Damage: 7

Bree bite Attack: 9 Damage: 12

(Unless the above attacks kills someone...)

The attack triggers the reactions and Bree hits the injured mastiff back KILLING it

Faleon, you can use your reaction attack

Faleon blasts poison breath at the Mastiff, forcing a DC13 DEX save from it, taking 12 poison damage on a failed save, or half damage on a successful save.

"BREE!  No more puppies!  I officially hate dogs!"

Mastiff save: 17

The mastiff gets a face full of poison but sneezes some out and suffers 5 dmg

That brings us to Gallo

Gallo readies his whip and says, "Yes, but what if we had some on our side as well?!"

He makes a couple of lightning fast flourishes, the tip of the whip cracking the air in a few spots around him... and in each of those spots appears a tiny sprite-like ghostly warrior (bonus action: entering the rage as a barbarian of the path of the ancestral guardian). He then lashes out along with all the tiny warriors at the remaining mastiff:

Attack: 8 Damage: 8

But he is Lucky afterall, so the there is a quick feint at the front paw of the mastiff while the actual hit comes right at the snout. Here's the new attack roll: 26

As this surely hits the dog then the following also applies:

Starting when you choose this path at 3rd level, spectral warriors appear when you enter your rage. While you’re raging, the first creature you hit with an attack on your turn becomes the target of the warriors, which hinder its attacks. Until the start of your next turn, that target has disadvantage on any attack roll that isn’t against you, and when the target hits a creature other than you with an attack, that creature has resistance to the damage dealt by the attack. The effect on the target ends early if your rage ends.

(hell of a lucky re-roll:) Gallo with his spectral warriors surrounding him cracks the whip right into the mastiff's snout splitting it's nose open causing 8 dmg

The spectral warriors continue to harass the mastiff.

That brings us to Oscar.

(I'm going to go for Oscar. I know he sometimes gets busy over the weekend so was giving him Monday to post. Anyways...)

Oscar swinging his mace at the mastiff.

Attack: 11 Damage: 7

Oscar doesn't connect on that attack.

That brings us to Faleon.

(OOC: I am very sorry! This weekend was indeed very busy and I thought I had made my way through all my games and posted but I apparently missed one. I am sorry :( )

(Truly no worries man! I would have acted for you sooner if I or someone else seemed anxious :)

Faleon will cast Shocking Grasp on the remaining Mastiff, hoping to get away from it.

Attack: 17 Damage: 2

Assuming that 24 is a hit, the Mastiff can't take reactions this turn, so Faleon will back away his full 25ft, keeping his eyes locked on the creature in what is an unsuccessful attempt to hide his fear and live up to his name.  Anyone looking at Faleon would notice his hands shaking and his bottom lip trembling, but Faleon assumes his friends are more focused on the Mastiff, and is at least relieved at that thought as he puts some distance between himself and the beast.

EDIT: Oh, also CON save for concentration on Dragon's Breath: 22

The spectral hand latches on to the mastiff causing 3 dmg. Faleon is able to maintain concentration. The mastiff shakes it off, still steady on its feet.

That will take us to Bree.

"Puppies need to be better trained."  Bree grumbles as she takes aim and shoots at the remaining mastiff.  She then tries to find a better hiding spot, since this one was not at all good last time.

Action: Shoot with crossbow.

Bonus Action: hide.

Movement: to better hiding place.

To hit: 8

Damage: 8 and 9 sneak.

Stealth: 23 / 22

Bree, your bolt flies straight and sinks deep causing 14 dmg. The mastiff staggers and some spittle mixed with blood flies out of its mouth as it attacks Faleon again.

Bite Attack: 14 Damage: 8

 (if that hits Faleon then he would take half damage due to the feature Gallo has)

(Thank you for pointing that out! I did roll at disadvantage but Faleon would only take 4)

Gallo whips at the dog once again (sorry, didn't realize it was my turn):

Attack: 27 Damage: 6

Faleon casts Shield as a Reaction, and the Mastiff's attack is blunted by an invisible force.  (Faleon is only at 3hp right now, so can't even afford to take 4!)