Katara, Bending Prodigy + Ashnod's Altar + Nadir Kraken + Biomancer's Familiar + Bard, King of Dale

Katara, Bending Prodigy

Ashnod's Altar

Nadir Kraken

Biomancer's Familiar

Bard, King of Dale

How it works

1. Activate Katara by paying 4 due to Biomancer's Familiar, causing you to draw a card.
2. Nadir Kraken triggers, causing you to pay 1 to put a +1/+1 counter on it and create two creature tokens.
3. Activate Katara by paying at most 2 and tapping the creature tokens.
4. Holding priority, activate Ashnod's Altar twice by sacrificing the creature tokens, adding CCCC.
5. Resolve the Katara ability, causing you to draw a card.
6. Repeat from step 2.

This intricate loop transforms Katara, Bending Prodigy's activated waterbend ability into an engine of endless value, heavily discounted by Biomancer's Familiar down to just four mana. When you draw that card, Nadir Kraken triggers to spawn tokens and grow itself, a production doubled right out of the gate by Bard, King of Dale's token-duplication replacement effect. Those newly minted bodies are instantly fed to Ashnod's Altar to generate the colorless mana needed to keep the cycle spinning, paying for both the Kraken's tax and the next activation of Katara's ability.