We are looking for a creature that could serve as an Adventurers League substitute for a colossal Baluchitherium (i.e. 100’ tall at the shoulder instead of 20’ and with hit points closer to a dragon) - which is no longer in 5e Dungeons and Dragons.
As more background - Adventurers League(AL) allows for game conventions to submit modules for review to be declared "AL Legal" for widespread use. A variety of guidelines must be met for acceptance. One regards monsters:
What monsters can I put in my adventure? You can choose from creatures in sources published under the Dungeons & Dragons brand such as the Monster Manual or Volo’s Guide to Monsters. You can modify them in small ways, such changing a bandit to an elf bandit using the rules Dungeon Masters Guide, or saying the party faces a large animated statue, but using the statistics of an ogre reskinned as that statue. You may not invent new monsters. The stat blocks in the adventure’s appendix must be faithful reproductions of the creature as found in its original product. Minor adjustments should be called out in a sidebar.
What could be a suitable AL creature that could be skinned to be a Baluchitherium but 100’ tall instead of 20’ and with proportionally more hit points?