Overview:

Dump mana into Proliferating Planeswalkers with Merfolk Skydiver and searching for creatures with Vivien's Arkbow. Then slam down a fat Bioessence Hydra on the opponents end step, thanks to Vivien, Champion of the Wilds and Wilderness Reclamation.

Notable Cards:

Merfolk Skydiver and Roalesk, Apex Hybrid:

• These cards allow you to put a +1/+1 counter on your creatures, allowing them to gain counters from Proliferate. A great target would be Carnage Tyrant.
• These cards can Proliferate your creatures and planeswalkers. Merfolk Skydiver has cost ability, whereas Roalesk, Apex Hybrid Proliferates twice upon death.
• Putting a +1/+1 counter on Incubation Druid early with Merfolk Skydiver activates its Adapt ability, allowing for more mana ramp which can be used to Proliferate further.

Bioessence Hydra:

• This is the main win condition. With a fresh Kiora, Behemoth Beckoner on the field, it will resolve as a 12/12.
• If both Kiora, Behemoth Beckoner and Vivien, Champion of the Wilds are fresh on the field, it will resolve as a 17/17.
• If both Kiora, Behemoth Beckoner and Vivien, Champion of the Wilds are on the field and you Proliferate, three +1/+1 counters are added to it. (One for each planeswalker and one from itself).

Vivien's Arkbow:

• Allows you to look for Bioessence Hydra and other creatures you may need.
• Hydroid Krasis is a mana efficent card to look for as you may be able to cast it the same turn, or on the opponents end step.

Vivien, Champion of the Wilds and Wilderness Reclamation:

• These cards allow you to cast creature spells on your opponents turn, preferably on their end step.
• Wilderness Reclamation allows you to float mana on your end step, so you can Proliferate twice whilst only having the land for one.
• These cards allow you to find a creature with Vivien's Arkbow and cast it on your opponents turn.
• With both these cards on the board, you effectively have double your lands to cast creatures with, as you can float the mana then play creatures after Wilderness Reclamation triggers, but still on your turn. Hydroid Krasis would be a creature to take advantage of this.

Kiora, Behemoth Beckoner:

• Starts with 7 loyalty counters, which is great for Bioessence Hydra.
• There are 12 creatures in the deck which can enter the battlefield with 4 power or more, which is great for card draw.
• The extra card draw can be used for the cost of Vivien's Arkbow.
• The -1 ability allows Incubation Druid to untap and tap again for an extra 3 mana, which can be used to Proliferate further.
• You could also use the -1 ability to ramp by untapping a Llanowar Elf or a land, potentially getting Bioessence Hydra out on turn 3.