Frost Giant

A frost giant on the party's side is a contracted skald, a sworn oath, or a debt of honor from a saga they took part in. Frost giants take pacts seriously and remember slights for generations, so the framing has to be specific: the party freed the giant's brother from a remorhaz pit, killed the white dragon that was eating its herd, or beat its jarl in a riddle contest with the giant as witness. Whatever it is, write the saga down and have the giant recite the relevant verse before any fight.

In combat, the giant is your party's cliff and your party's siege engine in one body. Open with War Cry on the party's heaviest hitter, not on itself. 16 temporary HP and Advantage on attacks for one round is the difference between the barbarian dropping the bandit chief and the fight running long. Then Multiattack with the Great Bow if the targets are clustered and far, or move into Frost Axe range if the party needs a wall. Two axe swings at 28 damage will end any low-CR enemy on the field.

Out of combat, the giant is a heavy and a guide. It carries the party's gear without complaint, breaks ice with its axe haft, and speaks Giant to creatures the party cannot. It will not fit indoors. Most doors do not admit a Huge creature, and most ceilings do not clear an 18-foot warrior. Plan scenes where the giant waits outside, or stage them in great halls and ruins.

When the agreed deed is done, the giant goes home. Have it leave a token with the party (a frost-axe carved with their names, a horn that calls it once more, a stone with a saga-rune). The token is worth one favor in extremity, and the party should know it.

A frost giant is a raider with a bow, not a brute that closes. The new GM's mistake is to walk it straight at the party and start swinging the Frost Axe. The right play opens at 150 feet with the Great Bow drawn. The giant is 18 feet tall, sees the party crest the ridge from a quarter mile out, and starts shooting before initiative is called.

Open with War Cry if it has it. Recharge 5-6 means roll for it before the fight; on a hit, the giant grants itself 16 temporary HP and Advantage on attacks until its next turn. Then Multiattack: two Great Bow shots at +9, range 150/600, 24 average per hit (17 piercing plus 7 cold) and the target's speed drops by 10 feet until end of its next turn. A melee party gets walked backward across the snow while the giant retreats and shoots. Frost giants are immune to cold and wading through their preferred terrain, so put the fight at the edge of a glacier or a river they can ford and the party cannot.

Once the party closes, switch to Frost Axe. Reach 10 feet, +9, 28 average per hit (19 slashing plus 9 cold). Two attacks a round on the same paladin will drop them in two rounds. Athletics +9 means a Shove to knock a PC prone or off the ledge the giant has been backing toward is a real option. Frost giants are not tactical geniuses (Int 9), but they understand high ground and that smaller things break.

A frost giant fights to the death only when it is defending a hold or a chief. Solo on a hunt, it withdraws once Bloodied, especially in weather it likes. Have it kick over a cairn of stones into a cliffside avalanche on its way out. The party should know it could come back with friends.