I have replaced Borborygmos with Sunder Shaman and Simic Sky Swallower with Winged Coatl , which lowered the average converted mana cost of this deck from 4.23 to 4.11, and those creatures are also better when copied.

I still feel that there is room for improvement in this deck; specifically, neither Ral Zarek nor Sarkhan Unbroken contribute to its overall theme, so I may possibly replace them. I already have Prophetic Bolt in this deck, but Ral's Outburst would be nice for its redundancy. Izzet Charm is nice, but Growth Spiral also is would be great for this deck. I also am hoping to find a way to put either Eternal Witness or Mulldrifter in this deck, and I wonder if I should replace Akroma, Angel of Fury , Niv-Mizzet, the Firemind , or Teferi, Mage of Zhalfir , as well; Bloodwater Entity would be a nice addition to this deck, since its abilities are cumulative when it is copied. What does everyone else say about that?

What about Dack's Duplicate ? Would that creature be good for this deck?

After much deliberation, I have replaced Niv-Mizzet, the Firemind with Bloodwater Entity , which lowered the average converted mana cost of this deck even further, from 4.11 to 4.06, because, as great as Niv-Mizzet is, the entity better suits the overall theme of this deck.

I also am considering replacing Edric, Spymaster of Trest with Coiling Oracle , but I am very uncertain about that; the oracle can be copied, but Edric is so amazing that I feel that any deck that can support his colors should contain him; what does everyone else say about that?

Also, if I do remove two of the three planeswalkers in this deck, I could likely replace Caged Sun with The Immortal Sun , which would be better in a three-colored deck.

I have replaced Ral Zarek with Ral's Outburst , because, while Ral himself is very awesome, the latter card better fits within this deck.

I have replaced Sarkhan Unbroken with Coiling Oracle , since the latter card is far better for this deck, which reduced the average converted mana cost of this deck from 4.06 to 4.02, and I also replaced Caged Sun with The Immortal Sun ; I know that I still have one planeswalker remaining, but he is in this deck primary for his triggered ability, and the possibility of drawing him in the same game as the sun is 2 out of 100, or 1 out of 50.

I have replaced Teferi, Mage of Zhalfir with Mulldrifter and Akroma, Angel of Fury with Flameblade Angel , replacements that I was very sad and unwilling to make, but the previous creatures were legendary, whereas non-legendary creatures can be copied by Riku, and the average converted mana cost of this deck has been further lowered from 4.02 to 3.98, so those replacements were definitely better for this deck.

I have replaced Mindcrank with Arcane Signet , since the former card did not contribute strongly to the theme of this deck, and it is always good to have additional sources of mana.

I have replaced Trap Essence with Ionize , because, while the former card is very awesome, it has two major flaws: first, it can counter only creature spells (if it could counter any spell, I would have kept it in this deck); second, if I do not have a creature on the battlefield, it's second ability does nothing. The latter spell, however, is much more versatile, and is useful in a much greater number of situations.

I have replaced The Immortal Sun with Caged Sun, since I do not wish to take the chance, however unlikely it may be, that I prevent my own planeswalker from functioning.

I am contemplating adding the new Twinning Staff from Commander 2020 to this deck, but I am not certain which card I could remove to make room for it.

Hey, could cut Vengeful Rebirth for Twinning Staff. Rebirth for six mana, eight mana if copying it with Riku, is too much for what it does even copied.

An advantage that Riku has as Commander with creatures are creatures who have good ETB abilities since the copy token also triggers an ETB ability which equals lot of value. Coiling Oracle and Mulldrifter are the right ideas, there's also Risen Reef which is especially good with the other Elementals in the deck since it triggers each time an Elemental creature you control ETB including token copies of Elementals. Clever Impersonator is very versatile in multiplayer Commander especially when you can copy it.

Thassa, Deep-Dwelling can be repeatable blink. Blink a nontoken creature at your end step and this triggers Riku letting you create a token copy of that creature for only two mana. Can be great value with Risen or any other creature with an ETB ability. Impersonator being blinked by Thassa can be pretty fun. Eternal Witness for repeatable recursion of any card. The Avatars and Horrors make a lot of devotion for Gods.

There's several difficult color requirements here to cast cards especially Avatars and when adding on Riku's copy ability. Chromatic Lantern helps a lot, so can Dryad of the Ilysian Grove as another total color fixing effect. 24x basic lands is a lot to meet these difficult color requirements consider more dual lands to help with color fixing? Ketria Triome, Exotic Orchard, Cinder Glade, Yavimaya Coast, Shivan Reef, Karplusan Forest.

Other ways to help color fixing are land ramp spells that search for a dual land. An advantage of the new Triomes that are Forests such as Ketria are land ramp spells that can search for a Forest or another land type. Nature's Lore, Wood Elves, Farseek, Skyshroud Claim. These spells also can search for Shock lands which you have, that can really help with color fixing.

Good luck with your deck.

I have replaced Caged Sun with Twinning Staff, which lowered this deck's average converted mana cost from 3.98 to 3.94; as great as the sun was, the staff is simply too good to not have in this deck, and the sun was the least essential artifact in this deck.

multimedia, I do not have a sufficient number of elementals in this deck to take advantage of Risen Reef, and your suggestions are great, but they would require a drastic reworking of this deck, and I would rather not do that, at this time.

Also, I have been wondering about the name of this deck: "Elemental Storm" does sound awesome, but it does not truly portray the nature of the deck; I have been considering "Double Trouble" as an alternative name, but that name is ridiculously cliched, at this point, so I would rather not use it. What does everyone else say about that?

If I have not said this, before, I really would like for WotC to print a creature version of Warstorm Surge since such a creature would be awesome in this deck.

I have replaced Warstorm Surge with Terror of the Peaks, which lowered this deck's average converted mana cost from 3.94 to 3.92, which is very good.

I have removed Comet Storm and Fable of Wolf and Owl and replaced them with Genesis Ultimatum and Dualcaster Mage, because those cards better work with the theme of this deck; doing so did increase the deck's average converted mana cost from 3.92 to 3.95, but that is only a minor increase, and I feel that it shall be worth the deck being better overall.

I am contemplating replacing Izzet Charm with Expansion / Explosion and Simic Charm with Repudiate / Replicate, because the split cards would work far better in this deck than would the charms; what does everyone else think about that?

After much deliberation, I have, indeed, made the replacement that I said that I would make in my previous post, and doing so did raise this deck's average converted mana cost from 3.95 to 4.06, but those numbers are deceptive, since a split card has the combined mana cost of both of its halves.

I have replaced Surrak Dragonclaw with Bramble Sovereign, which decreased this deck's average converted mana cost from 4.06 to 4.05 and also provides a creature that has amazing synergy with this deck.

congrats on saving 1/100th of a mana i guess?

JeanYass, are you being sarcastic or serious? I cannot tell, from a post on an internet forum, and is not any decrease in mana curve a good thing?

a decrease of 0.01 mana is entirely negligible, and a decrease in the first place is actually not always a good thing. less mana does not equal better.

JeanYass, that is true, but I replaced a creature who had no synergy with this deck with a creature who has great synergy with this deck; is that not a good thing?

surrak absolutely has synergy with this deck, because this deck has creatures. surrak has flash (letting you hold up mana for counter spells and removal) and helps ALL of your creatures for no additional mana. sovereign only helps "some" creatures (because only some of your creatures have stackable effects worth copying) and its also at the cost of 2 additional mana that you might not have or want to use. surrak will get +2/+2 from all 3 of your "liege" creatures, whereas sovereign will only get +1/+1, and only from the ones that affect green creatures. overall, surrak gives the bigger benefit to your creatures, while also receiving a bigger benefit as well.

JeanYass, that is very true, but I have decided that Surrak's benefits to other creatures in my deck are highly situational, so I would rather have a creature with more universal appeal, but I certainly do appreciate your feedback.

I have replaced Wreak Havoc with Hull Breach , which reduced the average converted mana cost of this deck from 4.05 to 4.02, which is great, and, as nice as it is to be able to destroy annoying lands, it is more important to be able to destroy two permanents for less mana, and I am certain that an average game shall have a greater number of annoying enchantments than of annoying lands.