Start the match with 1 Jewel of Vitality, Refillable Mana Potions and 2 Mana Potions.
When you recall to base buy up to 4 Jewel of Vitalitys. This gives you a lot more Mana recovery to keep healing throughout fights. If you have little bit of Gold left, you can also buy some more Mana Potions. Activating Rechargeable Mana Potions and regular Mana Potions at the start of a fight makes it unlikely for you to run out of Mana.

Then start building Star's Grace. Star's Grace grants your Carry CC immunity, so when a fight starts you can save your Carry from enemy CC. Especially Ults from Riktor, Countess, Kallari, Khaimera etc. Plus it gives you a much better chance to finish your Ult.

Your second item should be Victorious Footstep or if the enemy team has a lot of CC build High Priest's Consolation as your second item.

If your team is lacking in the frontline and you're dying too fast, you can build some of the optional items after you completed Star's Grace.

Recovery as a Karma is nice because it provides you with Mana and your Carry with HP, but you can also use Silence alternatively. Active your ult, then when the CC immunity runs out activate Silence.