Am I going to TPK my party if I do this?

[CigarPete]

We are in Cult of Cinders and they about to start exploring. The party is 6 players and there has been very little challenge in combats so far. I'd like to sub out the drakes (3 at CR6 vs 6 players) with young green dragons (2 at CR8 vs 6 players). Or would I be better off going with one dragon and one drake?

Party is Barbarian, Cleric, Champion, Alchemist, Sorcerer and Monk, all 6th level.

I'm fine with killing one or maybe two PCs if it comes to that, but I'd prefer not to slaughter the lot.

[Uchuujin]

In theory it's balanced, or even slightly under the current severe encounter budget of that fight. In practice fighting a level+2 foe is noticeably more difficult a equal level foe, and requires different tactics.

If your group is good at debuffing and group tactics that can help power down the enemies then though should be alright. If they are more accustomed to just battering down with brute force and AoE damage, then they may have more trouble with it.

[Kennethray]

I'm up to a 6 pc party and I will tell you what I did. Since one of my players is playing the last wall archetype with the cursed family background I added one of the monkey butchers with the grave knight template. He was lying beside the pillar and wouldn't "activate/die" until someone was beside him. I was using the swamp map so all the difficult terrain. However the sorcerer cast haste then jump on the rogue round 1, then the rogue was beside the pillar. Made for a very interesting fight as the drakes tried to fly off with the goblins and the cleric got too close to the grave knight and tasted that sweet sweet counteract.