  ASASSN-14dx showed an extraordinary outburst whose features are the small
outburst amplitude (~ 2.3 mag) and long duration (> 4 years). Because we found
a long observational gap of 123 d before the outburst detection, we propose
that the main outburst plateau was missed and that this outburst is just a
"fading tail" often seen after the WZ Sge-type superoutbursts. In order to
distinguish between WZ Sge and SU UMa-type dwarf novae (DNe), we investigated
Gaia DR2 statistically. We applied a logistic regression model and succeeded in
classifying by using absolute Gaia magnitudes $M_{G}$ and Gaia colors $G_{\rm
BP}-G_{\rm RP}$. Our new classifier also suggests that ASASSN-14dx is the best
candidate of a WZ Sge-type DN. We estimated distances from the earth of known
WZ Sge stars by using Gaia DR2 parallaxes. The result indicates that
ASASSN-14dx is the third nearest WZ Sge star (next to WZ Sge and V455 And), and
hence the object can show the third brightest WZ Sge-type superoutburst whose
maximum is $V$ = 8-9 mag.
