Ice Barrier Runick

You can refer to Beginner's Guide to Ice Barrier Runick (Post-BLTR) - YGOPRODeck for some analysis on how this deck works

As for the changes I made to that list: Deep Sea Diva is another awesome Normal Summon that opposed to Revealer won't eat up one of your hand cards so you have more possible discards and/or extenders. With Diva you basically have another 3 copies of Hexa (You can also bump Hexa up to 3 if you want since he, Revealer and Diva are your best Normal Summons and not having a Hexa in deck turns Diva into a dead card in hand)

Most of your combos are pretty well insulated with enough pivot potential to still stay a major pain in your opponent's resources.

If you only have Hexa and a Runick card, start your turn by normal summoning it and try to dump Mirror Mage for the basic combo which is insulated against Nibiru.

Should Hexa get Impermed/Ashed or Veilered, then you can easily pivot into just Lancea with Sleipnir summoned via a Runick Spell (playing it safe) OR (while not safe from Nibiru) if you have a second Runick Spell in hand, you can summon Hugin in your Draw Phase and bait out an Ash or search Fountain, Summon Hexa and should he get negated here, you can also make Spright Sprind with Hugin and Hexa to dump Mirror Mage anyway and search for Freezing Chains. If you have Georgius in your hand as well then you can make a lvl 10 and a lvl 8 from here by activating Freezing Chains, reviving Mirror Mage, Summoning Georgius (for no Revive since field slots wouldn't be enough for the tokens), activate Mirror Mage's effect to tribute Spright Sprind (a cost that clears your EMZ and the Water Synchro lock only applies when the Tokens are summoned) BUT chain the second Runick Spell to summon Geri (and draw 2 off of your Fountain if you were allowed to search it) and Synching off Georgius and Geri for the 10 and the lvl 5 Mirror Mage for whatever. If your Sprind gets negated as well though, then you might have a bad time...

If there is no Georgius in your hand you can still revive Mirror Mage with Freezing Chains and to the chain thing to either get Geri, Hugin or Sleipnir. In this case you'd use Geri, Mirror Mage and a Token for a level 10 (preferreably Lancea). Since the Tokens are called "Ice Barrier Token" you'd only need one more Ice Barrier Monster (Lancea sadly doesn't count as one but will gladly provide should your opponent Special Summon something) to protect our IB monsters from the activated effects of Extra Deck monsters (hidden effect of Freezing Chains go brr).

Should you choose your second Hugin you can either make an 8 that can't be destroyed once or a 10 with no leftover tokens.

If you choose Sleipnir then you probably won't use that one for a summon this turn unless you can revive a Hexa somehow (Georgius would come in handy there) so you'd probably end on Sleipnir for some control options with a level 8 synchro in tow

As for Deep Sea Prima Donna, since Runick love banishing the opponent's deck we have a lot of safe choices we can return to the opponent's hand to extend with her by either going through Revealer or just ending on a Barrier Statue of Torrents (I'd rather put that one into the Side Deck though as a preference and if they don't expect it it can be dropped on your opponent in game 3 if they have sided against everything else the Runick portion of the deck does)

Otherwise Sauravis is a fun card to search off of Herald when he tributes himself and the rest of the Extra Deck is tools for going second since Runick is a pretty strong engine and the deck can play through a good chunk of interruption by itself

Graydle Dragon can also be switched for White Aura Whale, this is just a lvl 8 Synchro slot to board break (Graydle Dragon is also genuinely a better choice due to not being limited to attack position monsters but also a bit more expensive than Whale since it only had the one printing 9 years ago)

As for the Deep Sea Prima Donna, she's a decent addition to keep on extending from just a Mirror Mage (with tribute fodder) or as simple protection for your Dragite since Synchros that use her can't be targetted by monster effects. Or you're being cheeky and use her first effect to cheat out a Barrier Statue (which I prefer to keep in my side deck for game one to scope out my opponent first)

Wayne is another fun extender when you're going second or an additional floodgate to turn off backrow deck's recursion while also just searching for Medaillon or Chains

Defender of the Ice Barrier is a fun little anti-Tenpai tech

You can also run some more generic floodgates like Powersink Stone, TCBOO and such but those aren't really my style