What traits does Gragas have in TFT Set 17?

Gragas has Psionic and Brawler.

Does Gragas scale with AP or AD?

Gragas's ability Chemical Rage scales with Ability Power.

Gragas is a 2-cost unit, so it's a common reroll candidate in TFT Set 17.

Gragas's hero augments are Self Destruct.

Chemical Rage: Heal over 2 seconds.

Chemical Rage
Heal   over 2 seconds. Then, deal   magic damage to target and enemies adjacent to them and 30% Chill them for 2 seconds.

Your team gains 5% Health. Brawlers gain more.

Gain Psionic items that can be equipped to any ally.

Heal

Restores Health to a unit, capped at maximum HP.
Slow

Reduces the target's attack speed for a duration. Patch 17.1 renamed this keyword from "Chill"; it does not affect movement speed.

Max Health

Grants the unit additional maximum HP, either flat (like +150 Health) or percentage (like +6% max Health). It comes up whenever you stack Giant's Belt items, pick health-boost augments such as Yasuo's Golden Hex or Giant and Mighty, or play Cho'Gath, whose cast permanently raises his own max Health every time he eats an enemy. For the cross-round permanent stat-stacks angle specifically, see the dedicated permanent stat-stacks page.

Gain a Gragas. Your strongest Gragas becomes a Magic Fighter with a massive explosion, but also damages himself.