Rashmi as a deck is primarily a massive suite of answers, a moderate selection of draw, and a very small wincon package, which means the pool of potentially viable cards in this deck is huge, and often interchangeable, as well as being subject to the needs of your meta.
Rather than clutter up the main list with an enormous list of maybe cards, I've put all the ones I've considered in this section.
Cantrips And Draw
Ancestral Vision ; Anticipate ; Careful Consideration ; Flash of Insight ; Opt ; Peer Through Depths ; Serum Visions ; Think Twice ; Thirst for Knowledge
This is a far from exhaustive selection of draw spells and cantrips that my list doesn't run currently, but are all playable in the deck.
Countermagic
Annul ; Complicate ; Condescend ; Disallow ; Dissolve ; Ertai's Meddling ; Forbid ; Logic Knot ; Mindbreak Trap ; Miscalculation ; Misdirection ; Power Sink ; Spell Blast ; Spell Burst ; Spell Snare ; Supreme Will ; Syncopate
I've tried to avoid any counterspells that merely bounce spells, or ones that draw opponents cards (looking at you, Arcane Denial) in these suggestions, but all of these are weaker/more conditional counterspells that are only run as Rashmi wants all the good countermagic, and then some.
You may have to dig a little deeper into these if you're constructing a more budget version of this deck, but these are all - at minimum - playable in Rashmi, albeit nowhere near as good as cards like Swan Song, Force of Will, or Mana Drain.
Regrowths
Eternal Witness ; Nostalgic Dreams ; Reclaim ; Regrowth
In terms of overall versatility, I'd recommend Regrowth and Reclaim the most out of these, but Eternal Witness does prove some nice combo lines you can use to expand your avenues of victory post-Enter the Infinite. However, without the creature synergies of other Simic decks, it's most just a three cmc Regrowth before that, which is less impressive. Nostalgic Dreams is the weakest of these four, but does allow us to get multiple cards back for two green.
Extra Turns
Time Warp ; Capture of Jingzhou ; Temporal Manipulation
Lacking the ability to really chain extra turns like Edric has always made these cards somewhat mediocre in my experience with Rashmi: more or less five mana Explores. That being said, running Capture or Temporal as a one-of is totally viable, either as an alternative to running Hurkyl's Recall or as a tertiary combo piece.
To explain the combos:
A. Post-Enter the Infinite, with Seasons Past as the last card in your libary:
i. Cast your extra turn spell.
ii. Take your next turn, drawing Seasons Past.
iii. Cast Seasons Past, turning the extra turn spell and whatever else you’d like to your hand.
iv. Repeat infinitely, slowly killing your opponents with creature beats.
B. Post-Enter the Infinite or not, with an extra turn spell, Noxious Revival and Isochron Scepter.
i. Cast your extra turn spell.
ii. Cast Isochron Scepter imprinting Noxious Revival.
iii. Either that turn or the next upkeep, activate Scepter to return your extra turn spell to the top of your deck.
iv. Repeat infinitely, slowly killing your opponents with creature beats.
C. With Seasons Past; an extra turn spell, and a tutor that finds Seasons Past (i.e. Mystical Tutor, though in a pinch Intuition works if you run at least two Regrowth effects, or Personal Tutor if you wish to run that).
i. Cast your extra turn spell.
ii. Cast Mystical Tutor finding Seasons Past.
iii. Take your next turn, drawing Seasons Past.
iv. Cast Seasons Past, returning Mystical Tutor and your extra turn spell to your hand.
v. Cast your extra turn spell, then use Mystical Tutor to tutor Seasons Past the top of your library.
vi. Repeat endlessly, taking infinite turns while slowly drawing your deck with Rashmi triggers. Bounce your opponents' creatures and win with creature beatdown over many turns.
The last of these requires at least twelve mana available to start the loop, so like Enter The Infinite, it's more of a late-game win.
Other Cards For Your Consideration
Back to Basics
An extremely powerful hate enchantment, I'd strongly recommend this where your opponents are primarily 3-5 color decks. The preponderance of 1-2 color decks in my meta is the only reason this has been cut.
Capsize
Alright as universal bounce with buyback, this is much better if you're running Paradox Engine where Capsize and enough non-land permanents to tap 5UU will net you mana each cast. Consider it mostly in conjunction with that card.
Cursed Totem
A powerful hate card, this is strong, but also requires a significant retooling of the deck to use properly. Here is an example deck list designed to exploit its potential.
Mystic Confluence
A nice Swiss Army knife of draw, countermagic, and bounce. It's gone in and out of this deck: it's good, but just slightly over-costed for our purposes, especially early-game.
Paradox Engine
I've found this card to have very little utility in Rashmi pre-combo turn, but it does open our combo suite considerably, working with buyback spells and enough permanents that tap for mana; expanding the Isochron Scepter combo to that card, Paradox Engine, and any instant imprinted on Scepter; and making Seasons Past loops net mana without Dramatic Reversal if needs be. That being said, I haven't (so far) found it necessary for this deck.
Personal Tutor
Given how heavily this deck is tuned towards instant-speed responses, Personal Tutor has always felt suboptimal for me. However, finding our wincon and several good draw spells is doubtlessly relevant, if you feel you wish to include it.
Psionic Blast
A very odd, out-of-the-color-pie card that can remove most relevant creatures, and also can double as a win condition if we loop it targeting opponents, after looping Nature's Claim and any artifact to give ourselves infinite life.
Rhystic Study
A powerful mix of stax and draw, this is mostly out do to my meta becoming slower and people paying its tax too readily. Good generally, but best against the greediest decks. I recommend you test it and decide how you feel about this card.
Seeds of Innocence
The best artifact wrath, this might be useful in more stax heavy metas. So far I've felt comfortable enough around stax heavy pods that I've not had a need for it.
Whir of Invention
Significantly better if you're running either more artifact based combos, or hate such as Cursed Totem or Grafdigger's Cage, but in a pinch an instant-speed Mana Crypt, end of turn. The first artifact tutor I'd run in Rashmi, if I wished to run artifact tutors again.
Winds of Rebuke
A solid bounce card that can double as a wincon if looped endlessly.