Aetherwind Basker does not have summoning sickness.
Steps
Declare
Lightning Runner and
Aetherwind Basker as attackers, triggering their abilities.
Resolve the
Aetherwind Basker trigger, causing you to get at least six ({E} magic symbol) .
Resolve the
Lightning Runner trigger, causing you to get ({E} magic symbol) ({E} magic symbol) , and then pay eight ({E} magic symbol) to untap all creatures you control and to get an additional combat phase after this one.
Repeat.
If you control more than six creatures, this combo will net infinite ({E} magic symbol) .