2023 Advent Calendar Day 15: Ancient Blizzard Dragon (monster)

Ancient Blizzard Dragon

Huge dragon, lawful evil
Armor Class 18
Hit Points 422, bloodied 211
Speed 50', fly 50'
STR 24 (+7), DEX 18 (+4), CON 27 (+8), INT 22 (+6), WIS 23 (+6), CHA 22 (+6)
Saving Throws Str +14, Con +15, Wis +13, Cha +13
Skills Perception +13, Stealth +11
Damage Immunities cold
Condition Immunities charmed, frightened
Senses darkvision 120', passive Perception 23
Languages Draconic, Primordial (Glacian), understands Common but will not deign to speak it
CR 22

Traits

Ice Walk. Unaffected by difficult terrain made of ice or snow.
Freezing Winds. Any creature that ends its turn within 5' of the blizzard dragon is pushed up to 15' to a space of the dragon's choice.
Sudden Flurry. When the dragon takes cold damage, each enemy in its Freezing Winds aura is moved up to 10' to a space of the dragon's choice.
Clumsy Flier. While flying, the dragon has disadvantage on attack rolls, and Strength and Dexterity saves.
Legendary Resistance (3/LR).

Actions

Multiattack. 1x Bite + 1x Claw, or 2x Claw.
Bite. MWA, 15' reach, +14 to hit, 2d8+5 piercing + 1d8+5 cold and target's speed reduced to 0 until the end of the dragon's next turn.
Claw. MWA, 15' reach, +14 to hit, 2d6+8 slashing + 2d6+8 cold, and target is pushed up to 20' to a space of the dragon's choice.
Deep Freeze (1/SR, must be bloodied). Each creature within 25' of the dragon must make a DC 22 Constitution save. On a failure, it takes 3d10+5 cold damage, and its speed is reduced to 0 and it has disadvantage on Constitution saves (save ends, DC 15). On a successful save, it takes half as much damage, and the effect lasts until the end of the dragon's next turn.

Bonus Actions

Rising Winds. If the radius of the dragon's Freezing Winds aura is less than 25', it expands by 10'. If it is 25', each creature within the aura must make a DC 22 Constitution save. On a failure, it takes 4d8+12 cold damage and falls unconscious (save ends, DC 15). The radius then resets to 5'.

Reactions

Chill Rebuke (1/SR, recharges when first bloodied). When the dragon is hit by a melee attack, each creature of the dragon's choice within 25' must make a DC 22 Constitution save, or it takes 1d10+16 cold damage and its speed is reduced to 10' (save ends, DC 15).

Legendary Actions (3/round)

Wing Blast (costs 2). Each creature in the dragon's Freezing Winds aura must make a DC 22 Strength save or be knocked prone. The dragon then flies up to half its speed.
Detect. The dragon makes a Perception check.
Cantrip. The dragon casts a cantrip.

Spellcasting

The dragon's spellcasting ability is Intelligence (+13 to hit, save DC 21). The dragon knows the following wizard spells:

Cantrips:
 - Frostbite. 60', CON save, 3d6 cold & disadvantage on next weapon attack
 - Ray of Frost. 60', attack, 3d6 cold & speed reduced by 10 until start of dragon's next turn

5th level (Recharge 4-6):
 - Expeditious Retreat. CONCENTRATION, BA Dash when cast and for duration
 - Thunder Step. Teleport up to 90', all within 10' CON vs 5d10 thunder, save 1/2
 - Counterspell. 60', negate spell cast of 5th level or lower, roll (+6 vs 10+spell level) for to negate higher levels
 - Magic Circle. (Only affects humanoids)
 - Absorb Elements. Resist triggering elemental damage, +5d6 of same type on next melee attack

Lair Actions

Falling Icicles. 3 icicles fall down from the ceiling, targeting points in the lair. A creature underneath a falling icicle must make a DC 15 Dexterity saving throw or take 2d6 piercing + 1d6 cold damage. If the target fails by 5 or more, it is also restrained until the icicle is removed (action, DC 10 Strength check) or destroyed (AC 13, HP 13; immune acid, cold, psychic, poison; resist bludgeoning, slashing, radiant; vulnerable fire, thunder).
Ice Spikes. A 10'x10' area in the lair grows jagged ice spike. A creature in that space when the spike appear, or that enters the space, must make a DC 15 Dexterity save or take 2d6 piercing + 1d6 cold damage, or half as much on a success. A creature that ends its turn in the spikes takes this damage automatically. If the target fails by 5 or more, it is also restrained until it is broken free or the spikes are destroyed (as icicles, 18 HP per 5'x5' section).
Summon Minion. The dragon summons an icy minion to a space in its lair. A minion is accompanied by 1d4-1 Winter Sprites if none are already present. d8: 1-2 Ice Mephit, 3-4 Ice Golem, 5-6 Winter Wolf, 7 White Pudding, 8 Frost Heave.

Good lord. Did I really write all that? For one stat block? This is a monster I've had hanging around for a while, and it's not really how I do things these days. I prefer something a lot looser and easier to absorb, that really gets to the heart of what makes the monster unique and interesting. But this type of massive complex stat block does have its advantages though: it's basically an entire encounter and battle map all in one (enormous) package.

Something I really like about this monster is that it really feels like fighting a blizzard. So many of its abilities are based on wind and forced movement, instead of plain old cold damage. It's really unique. And yeeting players into spikes, and pinning them to the ground with falling icicles... you can really see how the fight will play out, and all the awesome and dire moments, just from reading the stat block.

This is a pretty direct conversion of a 4th edition monster (from Monster Manual 3), a level 22 Elite Controller, to 5th edition numbers and action economy. I like 4e stat blocks and monster design, for their compactness, efficiency, and unique and interesting abilities on basically every single monster. Almost nothing in 4e is just a bag of hit points to poke at until it dies, which is one of my biggest problems with 5e and something I try hard to avoid in my own monster design. But 4e also has the advantage of good layout and shorthand, which requires a bit of system mastery to read and understand, but can also express interesting ideas in a compact, understandable format. (This tradeoff is something I think about often, and a post about it is in the works.)

The conversion is based on some dodgy math, plus a dose of whatever feels right. The damage output is significantly lower than what we might expect for a CR 22 monster, but it's meant to be a controller rather than a damage dealer, and it doesn't factor in throwing people into spike pits and summoning minions. I like the model 4e uses of a single damage die plus a large modifier (i.e. 1d6+10 rather than 3d6+3), it makes things a lot more predictable and less swingy, which fits with 4e's ethos. Transporting it to 5e, it softens the effects of crits against the players without removing the hurt entirely, which is nice. One interesting bit is the different save DCs for initial and ongoing effects - in 4e, the  DC for all ongoing effects is 10, regardless of the initial attack roll, which quickly becomes trivial at higher levels (at level 22 in 4e, you have at least a +11 bonus to everything). It gives players a taste of the full devastating effect, but without being shut out of the fight for several rounds. I recently played in a Halloween adventure with mind flayers, and being unable to do anything for a whole fight while trying to shake off being stunned was... not fun.

Of course, those are not the only changes. Legendary actions, legendary resistance, and lair actions are bolted on wholesale, with nothing remove to compensate. They all help boost the action economy, which is must needed - 4e could get away with one or two actions per round because the lack of bounded accuracy meant the dragon can almost always hit and the players almost never will (within the narrow range of levels for which the monster was designed); 5e needs more actions, to make up for always getting hit. Personally, I prefer the 5e model, since it keeps more monsters more relevant across more levels, and reflects an underlying reality in the game world, but "the treadmill" of 4e also works in its own context.

Spellcasting is also bolted on, simply because I think dragons should all be magical creatures, a fusion of esoteric wizardly arcana and primordial elemental energies. For the most part, the spells it uses are simple buffs or expansions of its action economy; nothing is a signature ability. Players will think of it as a dragon with a bit of spellcasting, not a wizard who happens to be a big scaly reptile. It uses my system for managing spellcasters without all the useless bookkeeping of a full spell slot system, where slots of a given level have a recharge like other abilities; there's no resource to track or complex decisions about what to save for later. It frees up a lot of brainpower for the things that actually make the fight interesting.