To Fusion Summon, the player must use a card or effect that allows for a Fusion Summon, such as the Spell Card "Polymerization", and have the appropriate monsters listed on the Fusion Monster as material in the locations listed by the Spell Card (usually in their hand or on the field)
The iconic holographic card was so beloved, that it used to sell for as high a $3,100
There is no universal schedule

Aetherstorm Roc Alania, Divergent Storm Ambling Stormshell Arrow Storm Brainstorm Brainstorm Breaching Dragonstorm Captain Lannery Storm Captain Lannery Storm Captain Storm, Cosmium Raider Chatterstorm Cinder Storm Colorstorm Stallion Comet Storm Command the Storm Conduit of Storms Contortionist Otter Storm Corroding Dragonstorm Crow Storm Descendant of Storms Desert Sandstorm Disruptive Stormbrood Disruptive Stormbrood Dragonstorm Dragonstorm Forecaster Dragonstorm Globe Dreadful as the Storm Echo Storm Elspeth, Storm Slayer Empyrial Storm Encroaching Dragonstorm Energy Storm Epiphany Storm Eris, Roar of the Storm Esper Stormblade Etali, Primal Storm Eye of the Storm Firestorm Firestorm Hellkite Firestorm Phoenix Flusterstorm Fury Storm Genesis Storm Gigastorm Titan Gravestorm Hail Storm Hailstorm Valkyrie Hall of Storm Giants Harness the Storm Harnesser of Storms Human Torch, Johnny Storm Ice Storm Imotekh the Stormlord Invisible Woman, Sue Storm Ion Storm Joyful Stormsculptor Kalamax, the Stormsire Keranos, God of Storms Kolaghan Stormsinger Kolaghan, the Storm's Fury Lava Storm Lightning Storm Lightning Stormkin Meteor Storm Mindstorm Crown Mjlnir, Storm Hammer Mouth of the Storm Nahiri, Storm of Stone Najal, the Storm Runner Needle Storm Neriv, Heart of the Storm Pigment Storm

Unfortunately, the way Mathas is worded is that only counters placed by his ability will trigger the card draw, but Bounty Hunter can still snipe any creature with a bounty counter including the ones placed by Mathas
U, Sacrifice Recantation: Return up to X target permanents to their owners' hands, where X is the number of verse counters on Recantation