Handtruck Not Included

Question: What is the viability of Birthrights like Chac Mools and the Stone of Destiny? Since you have to have your Birthrights physically with you, how do you practically use such giant Birthrights?

Giant Birthrights can give giant-sized benefits, but they are difficult to use, you're right. That's not necessarily a bad thing; it's just a feature of how they work and what their legendary role is.

While I don't think a Chac Mool statue (examples of which are usually solid rock and weigh in the neighborhood of 2 to 3 tons) is necessarily less viable than something more portable, it does come with unique challenges. Scions with such large Birthrights will need to keep them somewhere and return to them to use them, which adds an extra dimension to some of their tasks; I don't think this is necessarily a bad thing, as having to perform a sacrifice in the same ritual space or bring someone before the Stone of Destiny in its sacred hall is a cool part of the mythic weight of such things. The occasional nuisance of traveling to the relic instead of carrying it is easily offset by how powerful such nonportable things tend to be (the Chac Mool alone is an insane power level, particularly for Scions with higher levels of Itztli). In addition, such things become easily portable for anyone who picks up a few dots of Epic Strength later anyway, and Heroes who are not high enough Legend to do so yet are more likely to still be tied to locations and worldly concerns anyway.

If you're a Storyteller dealing with jumbo-sized Birthrights, just make sure not to constantly cockblock a player from getting to use theirs; in fact, making them the occasional focus of a story might actually reward that PC for their choice instead of punishing them, such as when they might need to defend the sacred site of their object from invaders, discovering important information in the process, or learn that its situation there has a specific purpose for the pantheon. If the band is preparing to go globe-trotting, a gentle reminder that the item will be left behind wouldn't go amiss for those Scions who have at least a normal level of Intelligence; you'd be surprised at how creative players can be when it comes to finding ways to move the normally unmovable or safeguard things in their absence, even if they don't have the easy outs of Epic Strength and/or Guardian boons.

The most important thing about plus-sized Birthrights is to make sure the player knows what they're getting into ahead of time. If you're considering one, think for a few minutes about what challenges it might present and whether or not you want to deal with it; if not, give it a pass. If you're storytelling, make sure you discuss it with a player ahead of time so that it doesn't come as a rude surprise when they find it's not quite as accessible all the time as they'd hoped (not every heroic quest can stay close to home, no matter how they might try).

Tangentially, the Chac Mool as written in the Scion books is kind of vastly overpowered; we tried giving it to a PC once and the results scaled into insane and unnecessary really quickly. It's all right at early Hero-level, but once things like Obsidian Excruciation and Poco a Poco get involved, shit gets crazy. The immovable nature of the Birthright is meant to counterbalance its insanely awesome benefits, but, as noted, it gets pretty easy to move a few measly tons once you have a couple dots of Epic Strength under your belt, so that really isn't enough to deal with the issue. I would probably avoid giving a PC anything that doubles Itztli's Legend gain; Itztli is nuts enough all by itself.

Chac Mools in general, however, are some of the coolest things on the planet, especially since in all technicality we have no idea what they mean, represent or were for. Scion runs with the most popular theory, that they were meant to be temporary receptacles for use during sacrifices, but that's really just an educated guess; not only do we not really know exactly what the Mesoamerican cultures used them for, we don't know who the reclining figure it supposed to be or what the imagery means. It's a neat place to speculate, especially since cultures like the Maya and Toltec were making Chac Mools before the Aztecs were, and you could come up with a lot of different ideas to personalize it for a specific game.