It's one of three prize cards from Japan's 2001 Second National Tournament
Destined on the stack is still a black instant with a converted mana cost of 2, and Lead on the stack is still a green sorcery with a converted mana cost of 4, but Destined to Lead, any time it's not one or the other, is a black and green instant sorcery with a converted mana cost of 6

A Trail of Teacups Aberrant Abundance Abundant Growth Abzan Beastmaster Advancing the Spirit Adventure Awaits Aggressive Urge Agonasaur Rex Airship Crash Altanak, the Thrice-Called Antique Collector Arctic Wolves Argothian Enchantress Armorcraft Judge Audacity Barkhide Mauler Barrier Breach Battle Mammoth Beast Whisperer Beastbond Outcaster Become the Avalanche Beneath the Sands Benefactor's Draught Bind Bind (playtest) Blessing of Frost Bloated Toad Bonds of Mortality Bookwurm Boseiju Reaches Skyward Braulios of Pheres Band Break Asunder Briarbridge Patrol Briarbridge Tracker Broodlord Bugenhagen, Wise Elder Built Bear (playtest) Burlfist Oak Byway Courier Cactarantula Caldaia Guardian Caldaia Strongarm Carven Caryatid Chalk Outline Champions of the Perfect Charge Through Claws of Wirewood Cloaked Cadet Coliseum Behemoth Collective Unconscious Colossal Majesty Communal Brewing Compost Concord with the Kami Confront the Unknown Contaminant Grafter Crystal Carapace Cultivator Colossus Curious Altisaur Darkwatch Elves Decree of Savagery Deepwood Denizen Dissenter's Deliverance Dosan's Oldest Chant Driven // Despair Drumhunter Earthshaker Dreadmaw Edge of Autumn Edgewall Innkeeper Eidolon of Blossoms Elder Gargaroth

Modern Horizons 3 Play Boosters each include the following: 14 Magic: The Gathering cards: 6 Commons* Modern Horizons 3 has 80 commons you can find in this slot
9 Nidoking BREAK In addition to a moderate 3-energy-cost attack that deals 120 damage, Nidoking BREAK inflicts a status condition to make the foe poisoned
While not explicitly lifegain, I think this commander offers a fresh take on the lifegain theme and directly converts your lifegain into a tangible resource (mana) as opposed to more +1/+1 counters or bonus life