Nice build. I've been playing with Rashmi for about a year and I am making adjustments now, and this has given me some food for thought.

Have you considered Constant Mists? It's ridiculously good with Rashmi, especially if you play in a creature-heavy meta.

Honestly I hadn't heard of Constant Mists until you mentioned it, however in my opinion given that its buyback is to sacrifice a land rather than discard, I would say the cost is too steep to buy it back and without the buyback it is a pretty bad card from an EDH perspective. In my opinion this deck wants to leave as much mana open to deal with non-creature spells as possible and to cast advantage cards (ie: fact or fiction) on the endstep before your turn. Additionally any land you sac is 1 turn longer you have to wait for Cyclonic Rift which is likely going to be the card that outright wins you the game. Health is a resource less valuable than mana, and I feel that Rapid Hybridization , Pongify, and Into the Roil provide enough combat step damage mitigation that adding in Constant Mists would not only be redundant, but also a bit "non-boish" with our "wincon"..