Based off Ravakahr's Config A build. His guide is very good so do go check it out.

My swaps:

Adaptation

• -> Narrow Mind, adjust the rank to tailor how long you want people frozen using your ult vs how small / target specific you want your bubble.
• -> Primed Vigor / Rolling Guard, different survivability.
• -> Carapice mods, health and armour with an option on effect, can help buff your bubble a little more.

Stretch

• -> Augur Secrets, increase the HP for a smaller bubble. This is less effective than using a carapice mod in place of adaptation.
• -> Constitution, to increase the cc of your avalanche from 6.2s to 8.4s.

Aura

• -> Corrosive Projection is great for its armour stripping.
• -> [Energy Siphon], help tick your energy up to fuel your shields.

Umbral Forma:
I'd forma the D polarity and swap an umbral mod with [Adaptation] to put it in an unpolarised slot. You could then use Blind Rage at Rank 2 for 27% more strength with max ranked Fleeting Expertise and Streamline.
With this, you can swap Stretch -> Augur Secrets if you want to boost the strength further, giving you these bubble stat changes:

• Snow Globe 1x goes from 15,890 -> 19,492 shield, for an energy cost of 12.5 energy.
• Cast Snow Globe 4x on exactly the same spot goes from 63,562 -> 77,970 shield, for an energy cost of 50 energy.
• With a max of 150 energy you can cast globe 12x before needing energy. 12 casts goes from 190,687 -> 233,910 shield.