This word uses the kun'yomi readings of the kanji. You haven't learned this reading for 殿 yet, so here's a mnemonic to help you:
Feudal Lords were pretty brutal back in the day. If you did something wrong he'd get to punish you. What kind of punishment? Well, he'd cut off your toe! That left most people yelling, "My toe?! NO!" (との). Imagine screaming "Toe no!" over and over as the feudal lord got closer and closer. Holding a pair of hedge clippers or something. Maybe if you yell "toe no" enough times, he'll change his mind.
I drew a handsome feudal lord to waste time.