Fiendsmith's Agnumday X LIGHT Link 3 [ FiendLinkEffect ] ATK 1800 DEF - 2+ monsters, including a LIGHT Fiend monster Once per turn (Quick Effect): You can target 1 LIGHT non-Link Fiend monster in your GY
Historically, Myutant has relied on a core of 2 Myutant Beast and 1 Myutant Arsenal, but because Shadow Severing Strike incentivizes us to play Myutant Mist (as banishing itself or another Spell can allow us to go +3 in terms of card advantage) were on a 1:1:1 ratio now
Which means you can use the effect, go through your plays and get a Rainbow Dragon or one of its variants on the field, and then during the Battle Phase you get to pick which of your Crystal monsters gets to use that effect
Heres how it works: If you Link summoned during your main phase, you can special summon Salamangreat Mole from your hand to a zone that a Link monster points to
ZEXAL episode 126: "Farewell for a Friend" a b c Yu-Gi-Oh
Seven Tools of the Bandit