Mega Venusaur ex has a whopping 380 HP and heals every time it uses its Jungle Dump
But its even better when you can cascade into it, say with Shardless Agent or Violent Outburst
Thats already a good ability, because it allows you to plan ahead

Abaddon the Despoiler Annoyed Altisaur Apex Devastator Ardent Plea Aurora Phoenix Averna, the Chaos Bloom Bigger on the Inside Bituminous Blast Bloodbraid Challenger Bloodbraid Elf Bloodbraid Marauder Boarding Party Call Forth the Tempest Captured Sunlight Cascade Seer Dark Apostle Demonic Dread Deny Reality Dreamroot Cascade Enigma Sphinx Enlisted Wurm Etherium-Horn Sorcerer Ethersworn Sphinx Flamekin Herald Forceful Denial Garbage Elemental Heralds of Tzeentch Imoti, Celebrant of Bounty Ingenuity Engine Into the Time Vortex Kathari Remnant Let the Galaxy Burn Maelstrom Colossus Maelstrom Nexus Maelstrom Wanderer Meteoric Mace Natural Reclamation Noise Marine Quandrix, the Proof Rain of Riches Sakashima's Protege Shardless Agent Skyline Cascade Sloppity Bilepiper Smoldering Stagecoach Stormcaller's Boon Sweet-Gum Recluse TARDIS TARDIS Bay The First Doctor The First Sliver Throes of Chaos Violent Outburst Volcanic Torrent Wild-Magic Sorcerer Wildsear, Scouring Maw Yidris, Maelstrom Wielder Zhulodok, Void Gorger

We've showcased the strategy before during GFC16
It's worth noting that many of these cards are no longer legal for competitive play as of March 22, 2024