Heroes vs. Dragons pt. II - encounter building help

[Specter]

Greetings. I need help planning an encounter (again).

In the previous thread (here (http://www.giantitp.com/forums/showthread.php?516745-Can-this-party-handle-these-young-dragons)), we discussed that for a party of level 11, four young dragons were too much. Now, I am considering throwing one young and one adult red dragon at them. The party is at level 12 now, except for the Vengeance Paladin who is at level 13. Kobold Fight Club says this is a 'deadly' encounter. The terrain doesn't include lava anymore, because it's not really a volcano, but more of a 'hot mountain'.

I ran a simulation, considering the usual party tactics and without lair actions, and they were defeated. The dragons lucked out on their breath recharge, and some rolls were pretty low on their side. The young red died, but adult red managed with around half his HP. Here's the simulation in portuguese, but it shouldn't be hard to understand:

PRÉ-COMBATE:
Sheela - Protection from Energy
Agar - Death Ward

SHEELA
init20, 95hp

YOUNG RED
init17, 160hp

ADULT RED
init13, 256hp

AGAR
init12, 90hp

BARDOCK
init11, 108hp

EBLIS
init8, 111hp

IRIKKI
init6, 98hp + 29temp
__________________________________________________ ______

TURNO 1
SHEELA
2 atks (+13), adult red
1o: hit, 1d8+5+2+1 (12avg)
2o: hit, 1d8+1d8+8 (17avg)
AR: -29

YOUNG RED
Fire breath (DX17; todos passam menos Eblis); 16d6 (56avg), Bardock - Shield Master, Irikki - Absorb Elements
A: -28
E: -56
I: +15
S: -14
Concentração Sheela: OK

ADULT RED
Fire breath (DX21; só Eblis passa); 18d6 (63avg)
A: -91 (Death Ward = 1hp)
B: -56
E: -87
I: -48
S: -45

AGAR
Call Lightning (5o nível)
Save young red: fail
Channel Divinity (max)
YR: -50
Action Surge: +1
Save young red: fail
Channel Divinity: max
YR: -100

BARDOCK
Lay on Hands (Agar): +65hp
A: +66
Bless (Agar, Bardock, Eblis)

EBLIS
Fly (Bardock)
Inspiration (Agar)

IRIKKI
Evard's Black Tentacles
Save young red: fail
3d6 (avg10), restrained
YR: -110
__________________________________________
TURNO 2

SHEELA
2 atks (+13), adult red
1o: hit, 1d8+1d8+8 (17avg)
2o: hit: 1d8+1d8(maneuver)+8 (17avg)
AR: -63

YOUNG RED
Recharge: YES
Fire Breath (Agar; fail)
Agar: +10
Concentração: fail automático

ADULT RED
Recharge: NOPE
Frightful Presence (aleatório: Sheela; fail, frighten)
Garrada (Eblis): hit, 2d6+8 (15avg)
Garrada (Eblis): hit, 15avg
Mordida (Irikki): hit, Shield (+2hp)
Eblis: DOWN

AGAR
Call Lightning (5o, young red)
Save: fail automático
50 (max)
YR DEAD

BARDOCK
Death Ward (si mesmo)

EBLIS
Lentamente abraçando o vazio (fail save de morte)

IRIKKI
Storm Sphere (6o nível)
Save: automático
Atk: fail
__________________________________________
TURNO 3

SHEELA
Atk (desvantagem)
1o: hit, 2d8+8 (17avg)
2o: hit, 2d8+8 (17avg)
Save Frightening: pass
AR: -97

ADULT RED
Recharge: **** YES
Deslocamento, Fire Breath (todos; só Agar passa, Irikki - Absorb Elements (+2hp))
21d6 (63avg)
Agar: DOWN
Bardock: 1 (Death Ward)
Eblis: goodnight sweet prince
Irikki: -75
Sheela: -86 (conc. fail)

BARDOCK
Branding Smite (Sheela)
Dodge

IRIKKI
Deslocamento
Lightning Bolt
Save automático
4d6 (14avg)
AR: -111
__________________________________________

TURNO 4
SHEELA
ATK
1o: hit, 2d8+2d6+8 (24avg)
2o: CRIT, 2d8+8 (17avg)

AR: -152

ADULT RED
Recharge? NOPE
Mordida (Sheela)
Hit: 2d10+8+1d6-parry(3) (22AVG)
Sheela: DOWN
Garrada (Irikki): Hit: 2d6+8 (15AVG)
Garrada (Irikki): Hit: 2d6+8 (15AVG)

I: DOWN

BARDOCK
Blinding Smite
Atk
1o: Fail
2o: Hit: 1d8+1d8+3d8+4d8(smite)+5+1 (47AVG)
AR: -158
__________________________________________

TURNO 5
Mordida: hit
Garrada: hit
Mordida: CRIT

THE DARKNESS COMES

So, a few questions:
1) How can I give the party an edge to aid in this endeavor? I've considered giving the paladin a potion of flying so that he can actually do some good smashing, but I'm open to ideas.
2) Would it be adequate to have an encounter with half a dozen half-red dragon veterans beforehand, or would that push things?

[Specter]

Bumping, because why not?

[krugaan]

How about two youngs? that still seems like a cripplingly close fight.

For added drama, have the red dragon crash into the party the round after they kill her last child. Enraged, blooded, and insane after a long fight with the copper, she seeks revenge for her fallen kits! Half health, no breath weapon, one wing wounded, so half speed flight.

If the party looks like they're going to get roflstomped, the severely wounded copper might struggle in there...

[Specter]

How about two youngs? that still seems like a cripplingly close fight.

For added drama, have the red dragon crash into the party the round after they kill her last child. Enraged, blooded, and insane after a long fight with the copper, she seeks revenge for her fallen kits! Half health, no breath weapon, one wing wounded, so half speed flight.

If the party looks like they're going to get roflstomped, the severely wounded copper might struggle in there...

Based on the experience I have with them, I think two youngs will be too easy. The party will probably barrage with stuff like Hold Monster and Polymorph until they cave, in which case the strikers can finish one of them in one round. Unless the youngs roll high on initiative and get very lucky with their breath, I can't see a scenario where this is a difficult match. But keep them coming!