  We present the first high-resolution chemical abundances of seven stars in
the recently discovered high-energy stream Typhon. Typhon stars have apocenters
>100 kpc, making this the first detailed chemical picture of the Milky Way's
very distant stellar halo. Though the sample size is limited, we find that
Typhon's chemical abundances are more like a dwarf galaxy than a globular
cluster, showing a metallicity dispersion and no presence of multiple stellar
populations. Typhon stars display enhanced $\alpha$-element abundances and
increasing r-process abundances with increasing metallicity. The high-$\alpha$
abundances suggest a short star formation duration for Typhon, but this is at
odds with expectations for the distant Milky Way halo and the presence of
delayed r-process enrichment. If the progenitor of Typhon is indeed a new dwarf
galaxy, possible scenarios explaining this apparent contradiction include a
dynamical interaction that increases Typhon's orbital energy, a burst of
enhanced late-time star formation that raises [$\alpha$/Fe], and/or group
preprocessing by another dwarf galaxy before infall into the Milky Way.
Alternatively, Typhon could be the high-energy tail of a more massive disrupted
dwarf galaxy that lost energy through dynamical friction. We cannot clearly
identify a known low-energy progenitor of Typhon in the Milky Way, but 70% of
high-apocenter stars in cosmological simulations are from high-energy tails of
large dwarf galaxies. Typhon's surprising combination of kinematics and
chemistry thus underscores the need to fully characterize the dynamical history
and detailed abundances of known substructures before identifying the origin of
new substructures.
