Redshift, Rocketeer Chief, and Seedcradle Witch

Prerequisites

• Redshift, Rocketeer Chief on the battlefield
• Seedcradle Witch on the battlefield
• available

Steps

1. Activate Redshift by tapping it, adding an amount of or equal to its power that can only be spent to activate abilities
2. Activate Seedcradle Witch by paying , untapping Redshift and giving it +3/+3 until end of turn
3. Repeat

Results

• Infinite colored mana that can only be spent to activate abilities
• Infinitely large creature until end of turn