Grounding techniques, I use my senses, 5 things I can see, 4 things I can hear, 3 things I can touch, 2 things I can smell and 1 thing I can taste. And usually by the time I've done that, it's over (I just have to deal with the migraine that follows).

Dumping your head in cold water or a cold shower will restart your body also you can try mindfulness/meditation but they way to combat panic attacks Is to look at your life and reflect is anything is stressing you out. Fear is the root cause of panic attacks Is there anything bothering you?

Grounding techniques are very good, but there is also a very thin line between anxiety and excitement in our brain. If you can find something in your mind that you are excited about in your near future or that's happening in your life, that can pull certain people out of panic attacks (that's what I do when breathing exercises and grounding exercises don't help me)

Videos of deep breathing help me it counts for you