  The neutral component of a real pseudoscalar electroweak (EW) triplet can
produce a diphoton excess at 750 GeV, if it is somewhat mixed with an EW
singlet pseudoscalar. This triplet-singlet mixing allows for greater freedom in
the diboson branching ratios than the singlet-only case, but it is still
possible to probe the parameter space extensively with 300 fb$^{-1}$. The
charged component of the triplet is pair-produced at the LHC, which results in
a striking signal in the form of a pair of $W\gamma$ resonances with an
irreducible rate of 0.27 fb. Other signatures include multiboson final states
from cascade decays of the triplet-singlet neutral states. A large class of
composite models feature both EW singlet and triplet pseudo-Nambu Goldstone
bosons in their spectrum, with the diboson couplings generated by axial
anomalies.
