Vulcan does well against gods who are vulnerable during or after they ult. His meatball is great for stopping channeled abilities and popping nem's shield. His backfire helps gain a small distance which is crucial to escape kali autos after she goes on you. Similarly, it can be used to escape certain abilities like scylla crush or danza ult. His meatball is also useful to CC gods with stuns who are about to stun you, making them unable to attack you while you are most vulnerable.

People that can gap close on Vulcan even with the use of his backfire are deadly. Also anyone with a criple or long last silence can easily mean the death to a Vulcan. Gods like Ne Zha and Zeus can bounce projectiles off of Vulcan's turret, making his 2 very hard to use effectively. Also, gods who can becoome untargetable like Hou Yi in his leap or Janus in his portal can counter an incoming Vulcan ult. Jing Wei is a special counter to Vulcan, making his meatball bad to use on her, even for the damage (this is due to her ability to escape while mid-air).

Guardians with setup, especially AOE setup is great for Vulcan ult. Awilix can make use of her ultimate with Vulcan's ability to knockup opponents fairly easily. Khumba and Ne Zha ults are extremely easy setups, since the opponent is unable to dodge the vulcan ult, or even aegis it.