  The phenomenon of pulsar nulling, where pulsars temporarily and
stochastically cease their radio emission, is thought to be indicative of a
`dying' pulsar, where radio emission ceases entirely. Here we report the
discovery of a long-period pulsar, PSR J0452-3418, from the ongoing
Southern-sky MWA Rapid Two-meter (SMART) pulsar survey. The pulsar has a
rotation period of ${\sim}$1.67\,s and a dispersion measure of 19.8\,\dmu, and
it exhibits both quasi-periodic nulling and sub-pulse drifting. Periodic
nulling is uncommon, only reported in $<1$\% of the pulsar population, with
even a smaller fraction showing periodic nulling and sub-pulse drifting. We
describe the discovery and follow-up of the pulsar, including a positional
determination using high-resolution imaging with the upgraded Giant Metrewave
Radio Telescope (uGMRT), initial timing analysis using the combination of MWA
and uGMRT data, and detailed characterisation of the nulling and drifting
properties in the MWA's frequency band (140-170\,MHz). Our analysis suggests a
nulling fraction of 34$\pm6$\% and a nulling periodicity of 42$^{+1.5}_{-1.3}$
pulses. We measure the phase ($P_2$) and time modulation ($P_3$) caused by the
sub-pulse drifting, with an average $P_2$ of 7.1$^{+26.3}_{-3.1}$ degrees and a
$P_3$ of 4.8$^{+1.5}_{-0.9}$ pulses. We compare and contrast the observed
properties with those of other pulsars that exhibit sub-pulse drifting and
quasi-periodic nulling phenomena, and find that the majority of these objects
tend to be in the `death valley' in the period-period derivative
($P$-$\dot{P}$) diagram. We also discuss some broader implications for pulsar
emission physics and the detectability of similar objects using next-generation
pulsar surveys.
