Have both of them, just got my titan to level 24 with these two helms...which should I use. Right now I have only worked on defender
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Helm of Sant 14 most of the time. Glasshouse during battle with atheon and crota (or applicable boss battles where you do not need to blind mobs) for longer duration of bubble. Likewise, when you are soloing lantern waiting for bridge to form. Extra 5 secs gives you more leeway and that you do not need to stall the ogre (by precision shooting him) as much before you pop the bubble.