All 40 Combos with Regal Behemoth

Springheart Nantuko + Overlord of the Hauntwoods + Spelunking + Regal Behemoth

Infinite Draw: Infinite ETB, Infinite creature tokens, Infinite landfall triggers, Infinite tapped Mountain tokens, Infinite tapped Island tokens, Infinite tapped Forest tokens, Infinite tapped copies of a specific land, Infinite tapped Plains tokens, Infinite tapped Swamp tokens, Infinite card draw, Infinite draw triggers

Declare Overlord of the Hauntwoods as an attacker. Overlord of the Hauntwoods triggers, creating an untapped Everywhere land token due to Spelunking. When the Everywhere token enters the battlefield, Springheart Nantuko triggers. Holding priority, activate Everywhere by tapping it, adding {G}. Regal Behemoth triggers, adding {G}. Resolve the Springheart Nantuko trigger, causing you to pay {1}{G} to create a token copy of Overlord of the Hauntwoods. When the Overlord of the Hauntwoods token enters the battlefield, it triggers, creating a tapped Everywhere land token. Repeat from step 3.