Results so far- D&D Test Monster Melee type - The Kid's party vs. Two CR 16ish monsters

 Not sure if they are really CR16 but has to be close-ish. 

• Took the 3.5e War Troll and 3.5e Fiendish Rage Drake... they were around CR 12. 
• Doubled their HPs.
• That means the Drake around 650 HP after a 40 HP powerup thingie (in 5e ver.2014, only the Tarrasque was high like that around 700-800.)
• Left their attacks and dmg the same, which seemed mostly right except
• the drake is doing like 34ish dmg per hit with claws... and has 2 claw attacks plus a bite. OMG. 
• Based their STR and CON and most stats on the Iron Golem (CR 16 in 5e). 

End result is... 

1. War Troll has AC 22, 280ish HP, 3 attacks so around 20, 20, 15 if it does all melee hits. 
2. Drake is like AC 13, 650 HP, 3 attacks so around 33, 34, 15 if it does all melee hits. Also had a one-time cold breath attack 8d10, ouch, hit ALL of them, knocked out the Elf first round. 

But get this... b/c of wall of stone and the big room they are all trapped in, the kid was able to "microwave" the drake. Sure enough, sickening radiance is insane b/c of exhaustion levels. Eventually it cuts HP to half, so down to 325 HP for the drake. And if went to Exhaust level 6, auto kill. 

So the drake is now dead, and the wartroll (made it immune to Radiant for testing)... is up next. He's about to get through the 3rd level of the stone wall so might actually be able to fight. Keep in mind, the two monsters won initiative, and (I was kind) killed off two wolves on the first round... but the drake got that cone of cold off 1st round and dropped the Elf. Didn't totally matter once wall stone trapped em b/c BonusAction heal from Druid to get Elf back up. Then the guys had time to heal back up to max or near max using the new optional "bonus action drink potion" stuff... but they really could have done it with regular actions anyway.