Fiery Hellhound

{R}: Fiery Hellhound gets +1/+0 until end of turn.

Neheb, Dreadhorde Champion

Trample
Whenever Neheb, Dreadhorde Champion deals combat damage to a player or planeswalker, you may discard any number of cards. If you do, draw that many cards and add that much {R}. Until end of turn, you don't lose this mana as steps and phases end.

Scrapyard Mongrel

As long as you control an artifact, Scrapyard Mongrel gets +2/+0 and has trample. (It can deal excess combat damage to the player or planeswalker it's attacking.)

Zodiac Dog

Mountainwalk (This creature can't be blocked as long as defending player controls a Mountain.)

Akoum Hellhound

Landfall — Whenever a land you control enters, Akoum Hellhound gets +2/+2 until end of turn.

Hellfire Mongrel

At the beginning of each opponent's upkeep, if that player has two or fewer cards in hand, Hellfire Mongrel deals 2 damage to that player.

Bolt Hound

Haste (This creature can attack and {T} as soon as it comes under your control.)
Whenever Bolt Hound attacks, other creatures you control get +1/+0 until end of turn.

Goldhound

First strike
Menace (This creature can't be blocked except by two or more creatures.)
{T}, Sacrifice Goldhound: Add one mana of any color.

Iron Mastiff

Whenever Iron Mastiff attacks, roll a d20 for each player being attacked and ignore all but the highest roll.
1—9 | Iron Mastiff deals damage equal to its power to you.
10—19 | Iron Mastiff deals damage equal to its power to defending player.
20 | Iron Mastiff deals damage equal to its power to each opponent.

Tesak, Judith's Hellhound

Unleash (You may have this creature enter with a +1/+1 counter on it. It can't block as long as it has a +1/+1 counter on it.)
Other Dogs you control have unleash.
Creatures you control with counters on them have haste.
Whenever Tesak, Judith's Hellhound attacks, add {R} for each attacking creature.

Bedlam

Underworld Rage-Hound

Underworld Rage-Hound attacks each combat if able.
Escape—{3}{R}, Exile three other cards from your graveyard. (You may cast this card from your graveyard for its escape cost.)
Underworld Rage-Hound escapes with a +1/+1 counter on it.

Mogis's Warhound

Bestow {2}{R} (If you cast this card for its bestow cost, it's an Aura spell with enchant creature. It becomes a creature again if it's not attached to a creature.)
Mogis's Warhound attacks each combat if able.
Enchanted creature gets +2/+2 and attacks each combat if able.

Immolating Souleater

{R/P}: Immolating Souleater gets +1/+0 until end of turn. ({R/P} can be paid with either {R} or 2 life.)

Ashmouth Hound

Whenever Ashmouth Hound blocks or becomes blocked by a creature, Ashmouth Hound deals 1 damage to that creature.

Blood Hound

Whenever you're dealt damage, you may put that many +1/+1 counters on Blood Hound.
At the beginning of your end step, remove all +1/+1 counters from Blood Hound.

Chandra's Magmutt

{T}: Chandra's Magmutt deals 1 damage to target player or planeswalker.

Pyre Hound

Trample
Whenever you cast an instant or sorcery spell, put a +1/+1 counter on Pyre Hound.

Komainu Battle Armor

Menace
Equipped creature gets +2/+2 and has menace.
Whenever Komainu Battle Armor or equipped creature deals combat damage to a player, goad each creature that player controls.
Reconfigure {4} ({4}: Attach to target creature you control; or unattach from a creature. Reconfigure only as a sorcery. While attached, this isn't a creature.)

Rousing Refrain

Add {R} for each card in target opponent's hand. Until end of turn, you don't lose this mana as steps and phases end. Exile Rousing Refrain with three time counters on it.
Suspend 3—{1}{R} (Rather than cast this card from your hand, you may pay {1}{R} and exile it with three time counters on it. At the beginning of your upkeep, remove a time counter. When the last is removed, you may cast it without paying its mana cost.)

Leyline Tyrant

Flying
You don't lose unspent red mana as steps and phases end.
When Leyline Tyrant dies, you may pay any amount of {R}. When you do, it deals that much damage to any target.

Wildfire Cerberus

{5}{R}{R}: Monstrosity 1. (If this creature isn't monstrous, put a +1/+1 counter on it and it becomes monstrous.)
When Wildfire Cerberus becomes monstrous, it deals 2 damage to each opponent and each creature they control.

Sterling Hound

When Sterling Hound enters, surveil 2. (Look at the top two cards of your library, then put any number of them into your graveyard and the rest on top of your library in any order.)

Igneous Cur

{1}{R}: Igneous Cur gets +2/+0 until end of turn.

Harnfel, Horn of Bounty

Discard a card: Exile the top two cards of your library. You may play those cards this turn.

Birgi, God of Storytelling

Whenever you cast a spell, add {R}. Until end of turn, you don't lose this mana as steps and phases end.
Creatures you control can boast twice during each of your turns rather than once.