Wojigairon

The Wojigairon (ウォージーガイロン) is a giant quadrupedal dinosaur-like Reaverbot from Mega Man Legends 2. It is the boss of the Saul Kada Ruins, attacking intruders with a shockwave, electric rings, a swat of its front legs, fire breath, lava rocks, and small fireballs. It can also drink lava to restore its health.

The young Digger must enlist the help of the Bonnes to cover the source of the lava going to Wojigairon's lair before he can destroy it for good.

Another Wojigairon appears in the Mother Zone of Elysium.

Floor 2F
The Wojigairon can be seen on the windows on the long hallway Mega Man walks on (about the same level as its "face"). If he is seen, the Wojigairon can bash its head in on a window, smashing it and damaging Mega Man if hit (also doubles as a jump scare).

Floor 3F (with Lava)
When Mega Man first properly encounters the Wojigairon, it is bi-pedal and impossible to defeat, because there is no lifebar for it and when it gets damaged enough, it will crawl towards the lava and then drink from it, restoring its health. It is recommended that you avoid fighting it if there is still lava in the room as to not waste time and Special Weapon Energy and the ruins force you to go through the boss room to get to other areas before you can take it down.

Floor 3F (without Lava)
After closing the source of the Lava, he now walks on four legs, has a lifebar and there's no more risk of falling into the lava as it has cooled down and hardened. He attacks by releasing electric rings and bashing his head down which sends a shockwave forward. It's weak spot is the jaw.

Trivia

 * Wojigairon's appearance and part of its name, "Gairon", is possibly derived from Guiron (ギロン Giron), a monster from the movie Gamera vs. Guiron.