Horseshoe Crab and Ley Weaver each have at least one +1/+1 counter on it.
You control up to two lands that can tap to produce at least ({U} magic symbol) .
Steps
Activate Experiment Kraj using Ley Weaver's ability by tapping it, untapping two lands you control.
Activate a land by tapping it, adding at least ({U} magic symbol) .
Activate Experiment Kraj using Horseshoe Crab's ability by paying ({U} magic symbol) , untapping Experiment Kraj.
Repeat.
You may tap an additional land each cycle to get infinite mana, and you may then use Experiment Kraj's ability to put infinite +1/+1 counters on creatures you control.