Karmic Guide + Saffi Eriksdotter + sacrifice outlet = infinite sacrifices and ETBs
How it works:
- Sacrifice Saffi Eriksdotter to activate its ability targeting Karmic Guide
- Sacrifice Karmic Guide, putting the delayed trigger from Saffi Eriksdotter on the stack
- Resolve Saffi Eriksdotter's delayed trigger, returning Karmic Guide to the battlefield
- Target Saffi Eriksdotter with Karmic Guide's enters the battlefield ability
- Resolve Karmic Guide's ETB ability, returning Saffi Eriksdotter to the battlefield
- Repeat