  In \cite{S}, Shyr derived an analogue of Dirichlet's class number formula for
arithmetic Tori. We use this formula to derive a Brauer-Siegel formula for
Tori, relating the Discriminant of a torus to the product of its regulator and
class number. We apply this formula to derive asymptotics and lower bounds for
Galois orbits of CM points in the Siegel modular variety $A_{g,1}$.
Specifically, we ask that the sizes of these orbits grows like a power of
Discriminant of the underlying endomorphism algebra. We prove this
unconditionally in the case $g\leq 5$, and for all $g$ under the Generalized
Riemann Hypothesis for CM fields. Along the way we derive a general transfer
principle for torsion in ideal class groups of number fields.
