If you generate a bunch of token creatures with a commander like Rhys the Redeemed or a lot of cheap, efficient creatures, each can tap to untap a basic land, ramping your mana at unreasonable speed
Raiyuu, Storm's Edge Raiyuu, Storm's Edge has a good attack trigger to be copied with Isshin, Two Heavens as One
Legendary Creature Artifact - Robot Color tag templates(None) Emissary Escort This creature gets +X/+0, where X is the greatest mana value among other artifacts you control
The exciting part of Unsettled Mariner is that its a changeling
There are some powerful item cards so playing Break to eliminate those cards from play can help turn the tide of the battle
Every time the ability triggers and resolves (and fails to transform the clone), it immediately triggers again, and so on, ad infinitum