For 100-Tonne Swing run out of range.

For 100-Tonne Swipe either run behind him or block it with Aegis Boon or Divine Veil, or take the hit with Sentinel or Hallowed Ground.

For Glower either run behind him or take it and cure yourself as he uses the ability.

For Animal Instinct you can use Shield Bash to buy some time for yourself and your party to react. Spamming Animal Instinct is about the most uncooperative thing Coincounter can do.

Beware of Amnesia from slugs. But if it affects you, remember that you can in principle dodge all of his one-shot attacks that you might otherwise want to use an ability to mitigate the damage from.

Lag of course is a myth and doesn't exist. But if it did, this is an encounter where it could be an issue, especially late in the fight when all of those slugs pop.

Good luck. I love Coincounter. He's really the only challenge for a tank in Aurum Vale.