Talk:Chroma (Warframe)/@comment-25793395-20151013164526/@comment-26835408-20151013210748

"Encases Chroma and affected allies in a layer of frost that increases base  armor  by  25% / 75% / 100% / 150%  and creates an ice shield that reflects incoming fire back to their source."

" Since Chroma has 350 base armor, a rank 3 Elemental Ward with +30% power strength will increase his current armor by  350 × 1.5 × 1.3 = 682.5  points"

Of what I can understand from the Elemental ward, it simply says that the base armor will be increased by 150%, not that it will be applied to the already existing armor. Meaning that if you actually have 350 armor on your Chroma to start off with, then activating the skill will give you 350 x 150 / 100 = 525 armor.

the equation you're looking for is most likely:

(New Base Armor = Base Armor x 150 x (1 + strength mod) )