Living End wants to dump its whole hand of creatures into the graveyard via cycling and Street Wraith before cascading into Living End for a massive reanimation swing. Endurance can both flash in as a 3/4 reach blocker to survive the Shardless Agent/Violent Outburst cascade turn and, more importantly, use its enter-the-battlefield trigger (or be evoked for free pre-cascade) to make them put their whole graveyard on the bottom of their library, which strips away the creatures they're about to get back and strands their combo. Since Endurance has flash, it's a great proactive or reactive answer either on their upkeep after suspend or in response to the Living End cast itself. We only make this small swap since our deck's game plan of fast ramp into big threats is already quite good at racing them if disruption isn't available.