  We consider compactifications of very Higgsable 6d $N =(1,0)$ SCFTs on $T^2$
with non-trivial Stiefel-Whitney classes (or equivalently 't Hooft magnetic
fluxes) introduced for their flavor symmetry groups. These systems can also be
studied as twisted $S^1$ compactifications of the corresponding 5d theories. We
deduce various properties of the resulting 4d $N=2$ SCFTs by combining these
two viewpoints. In particular, we find that all 4d rank-1 $N =2$ SCFTs with a
dimension-6 Coulomb branch operator with flavor symmetry $\mathfrak{e}_8$,
$\mathfrak{usp}(10)$, $\mathfrak{su}(4) $ and $\mathfrak{su}(3)$ can be
uniformly obtained by starting from a single-tensor theory in 6d. We also have
a mostly independent appendix where we propose a rule to determine the Coulomb
branch dimensions of 4d $N =2$ theories obtained by $T^2$ compactifications of
6d very Higgsable theories with and without Stiefel-Whitney twist.
