User blog comment:KrPa/Zirael, The Blood of Destiny/@comment-4977390-20130708152241/@comment-7481207-20130708161958

Suppress in itself doesn't mean the caster is affected, it is just a stun that disables all summoner spells rather than just Flash and Teleport and is also unable to be reduced tenacity. It just appears on channeled or caster disabling abilities because that's where a suppress is usually needed over a stun.