In Grappling arts, the counter is very often more powerful than the initial attack.
Seoi nage is a shoulder throw, one of the traditional forty throws of Judo as developed by Jigoro Kano. It belongs to the first group, Dai Ikkyo, of the traditional throwing list, Gokyo (no waza), of Kodokan Judo. It is also part of the current 67 Throws of Kodokan Judo. It is classified as a hand technique, te-waza.
The specific techniques of morote-seoi-nage (two hands seoi-nage) or eri-seoi are generally called seoi-nage. The distinctive technical aspect of this classification is that tori (the one executing the technique) grips with his two hands as opposed to Ippon Seoi Nage in which only one hand remains gripping while the other slides under uke’s (the one receiving the technique) armpit. Seoi nage is one of the highest-scoring techniques in Judo. Renown seoinage martial artists are Isao Okano and Toshihiko Koga. In BJJ, famous seoinage competitors include Saulo Ribeiro, Fernando Margarida, Ronaldo Jacare, and Rodolfo Vieira.
Katsuhiko kashiwazaki shows how to counter seoi nage with a clock choke:
Drop (knee) seoi-nage, sometimes called drop seoi-nage is a variation where you drop deeper than usual.
In this video, Multiple Australian and Oceania Champion and a 2008 Beijing Judo Olympian Matt D’Aquino of Judo for BJJ, shows 3 strategies and techniques you can do to stop or prevent your opponent for dropping in for a drop seoi nage: