Ertha Jo, Frontier Mentor, Kenrith, the Returned King, Crystalline Crawler, and Training Grounds

Prerequisites

• Ertha Jo, Frontier Mentor on the battlefield
• Kenrith, the Returned King on the battlefield
• Crystalline Crawler on the battlefield
• Training Grounds on the battlefield
• available

Steps

1. Activate Kenrith by paying , targeting Crystalline Crawler
2. Ertha Jo triggers, copying Kenrith's ability, targeting any creature you control
3. Resolve both Kenrith abilities, putting a +1/+1 counter on Crystalline Crawler and any creature you control
4. Activate Crystalline Crawler by removing a +1/+1 counter from it, adding
5. Repeat

Results

• Infinite colored mana
• Infinite lifegain triggers
• Infinite lifegain
• Infinite +1/+1 counters
• Infinite card draw for any number of players
• Put all creature cards from all graveyards onto the battlefield under your control
• Infinite draw triggers for any number of opponents