STEGOSAURUS
A late-Jurassic plated browser that trades speed for the single most punishing tail in the herbivore roster.
Stegosaurus is a standing fight. It cannot outrun anything that wants to kill it, so position matters more than reaction: keep your flank against terrain, keep the tail facing open ground and never let two attackers reach opposite sides.
The tail arc is the whole kit. A clean hit staggers mid-tier carnivores and stacks heavy bleed, but the swing is slow enough to be baited. Swing on committed approaches, not on feints, and step with the swing to keep the arc on target.
Low ferns, cycads and shrub layers cover almost all of the diet, so it grows fastest in dense inland forest rather than open plain. Water is the constraint: plan routes between drinking spots before growth pushes hunger up.