Different trinket sets for different fights. There are a lot of fights where you don't quite as much EHP as you do on Icehowl. The Ony trinket is giving you avoidance from the Parry, avoidance from the +Defense in terms of dodge / parry gain, as well as some additional chance to be missed. I toss on my Ony trinket when tanking things that my EHP is not a risk factor for.
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