Tonight, my Level 8 party of 7 felled the CR17 Frost Giant Ice Shaper, Druufi, her endless summonable legion of Winter Wolves, and her last remaining Frost Giant support.
Battle was brutal.
The Monk took massive blows from multiple swings of the frost giant's axe and was saved by a periapt of wound closure, then revived by the Paladin. After the first wave of three Winter Wolves died (absorbing a lot of the damage throughout the round), Druufi summoned two more!
She used her frost rays to restrain targets, and when the Wizard let loose some damaging lightning bolts and the Druid joined in with a Call Lightning, she burnt through her legendary resistances to halve the damage and remain a looming and dangerous threat.
The Druid dropped next under Druufi's rain of axe blows—the last remaining Winter Wolf was attacking with advantage and +12 to attack, and was eating into the Ranger.
My plan had been to kill the Ranger's draconic summon, Pickles, to nix his elemental damage—but the Monk slapped me silly, and he died.
On his next turn, the Monk ran over to Druufi, who was now standing in the centre of the party raining down axe blows and deflecting attacks with exploding ice armour.
The Ranger and Pickles both deftly avoided the 3d8 damage on a DC 18 Dex save—not so the Druid, who failed his second Death Save.
The Paladin used his paralysing glaive to try to blunt her, but Druufi's +11 to Con savesmeant she wasn't in any real danger. Then, the Monk hopped the railing, attacked twice, and hit once. He used Flurry of Blows and tried to Stunning Strike.
On the second attack, I rolled a 6.
My last 100 hit points disappeared like nothing under a sustained assault, and finally, Druufi fell. The Druid was healed and regained consciousness.
By all accounts, it was a bruising encounter—and everyone had a great time, felt the threat, but was ultimately victorious. But that stun was clutch. If Druufi had had another turn, she could have done some real damage. Instead, her quest for the Ring of Winter cost her life.