"1. Regrowth Pendant -> Warmogs Armor
2. Boots of Speed -> Mercury Treads
3. Banshees Veil
4. Atmas Impaler
5. Phage -> Frozen Mallet
6. Guardian Angel"
I think a Tankarina is good but too much hp will make her useless. I looked over your profile you have 159 wins, 47 of which with kat. Warmogs, frozen mallet, banshees, and guardian angel are all around 3k gold, making your build extremely expensive. Over 4k+ hp is a lil overkill. I think the 3k-3.5k hp mark is good enough in terms of survive and damage. I think you should focus more on AP. Ap items give mag resist, hp, and very good actives like zhonyas. The recommended for Kat actually works pretty well. For me i usually go boots>rylais>Zhonyas>guardian angel if i can get that far> maybe even a haunting guise. This will give you the survive you need and give you good attack damage to actually be useful in a team fight.