When Icathian Rain kills a Sett after 2 hits, when does the other Sett lose the buff from Kingpin (+1 Might for each friendly unit)?

Ruling: The other Sett loses the Kingpin buff immediately after the first Sett dies, before the next Icathian Rain ping resolves.

Sequence:

• First Icathian Rain ping resolves
• If this kills a Sett, cleanup occurs immediately
• The surviving Sett loses its Kingpin bonus Might during cleanup
• Next Icathian Rain ping resolves with the reduced Might value