I did the mandatory search of instants and sorcery that target permanents you control and a few patterns emerged.
Lots have in built replacement draw with either "Draw a card." or "Draw a card at the beginning of the next turn's upkeep."
In this manner you can efficiently draw into further spells like these.
Another element is that there are some that allow multiple casting and that might be via flashback, rebound, jump-start, buyback or cipher.
This means that you can look to get even more value from copying your cards.
There are a lot of cards that target creatures, but there are also a set that allow you to target some variation of permanents.
For example Thermal Flux can target any permanent, while Enervate can target artifact, creature or land.
Cantrip Mono-Blue Land Ramp
With Orvar, the All-Form you can use these types of cards to target a land and copy it, meaning you get incredible quantity and quality of land ramp in the deck. For mono-Blue this is almost unheard of.
There are 17 cards that can target lands and they all cost between 1-3 mana and either have a draw effect or are able to be cast multiple times.
Glamerdye is a great example of a card that you can cast multiple times. If you are copying a land then you create another mana so you can potentially cast it multiple times in a turn because you are adding lands that you can use to help cast it again.
Copying lands means that a few utility lands can be used for value or even infinite's.
There are 3 x buyback cards that can target lands in Whim of Volrath, Mind Games, Clockspinning. If you can produce enough mana each time you create a land to be able to cast with buyback then you can go infinite.
High Tide cast a couple of times with a cost reducer like Sapphire Medallion is an example of how you might do this.
These buyback cards are honestly one of the key elements to the deck in both in terms of great value and also game ending infinite's.
Mystic Sanctuary can be copied to put an instant or sorcery back on top of library.
Aquitect's Will is a one mana card which means that you can cast it to make another Mystic Sanctuary.
Timing of resolutions is important here. Orvar, the All-Form is a cast trigger so a token of Mystic Sanctuary is made while the Aquitect's Will is still on the stack, meaning you couldn't specifically target the Aquitect's Will.
But if you have another land targeting card (with draw) then you can put the Aquitect's Will on top and then draw it to cast again.
You can keep looping effects like this for as much mana as you have and remember a new land is being created each time which can be used to cast the spells.
There are no other target land cards that only cost one mana but Twitch (untaps a land meaning virtual 2 mana) and Shimmering Mirage only cost 2 mana and therefore with Sapphire Medallion only costing meaning that you could create infinite Mystic Sanctuary within these combination of cards.
Remember that Polluted Delta, Mystic Rainforest, Scalding Tarn, Flooded Strand can all get Mystic Sanctuary when you are ready for it.
High Tide is also a card that makes each land produce more mana so could be combined with other land targeting cards to really go off, if not infinite.
However you need 4 mana for Clockspinning and Mind Games to be able to create infinite Islands. Casting High Tide 3 times in a turn isn't really what the deck is designed to do but there are combinations of cards that can allow you to sequence this.
There are a bunch of efficient cantrip instant and sorcery that target creatures only. Therefore we want a set of creatures that are good to make duplicates.
Precursor Golem is like the signature card for the deck. You specifically copy the Precursor Golem creating 3 more Golems. Orvar, the All-Form is a cast trigger so you wouldn't be able to target the new copies yet, but it still an incredible cascading effect and because so many of your targeting spells contain draw you just get to draw heaps more cards for each Golem.
Sakashima of a Thousand Faces and Spark Double are able to copy Ovar. Because each time you cast a targeting spell you'll get to create another Ovar this has a cascading effect on number of Ovar you keep creating and the number of times a spell is copied.
These creatures are by far the most exponential way to take over a game by making creatures.
Enter the battlefield triggers are great for this to make sure you get value.
For card draw there is Augur of Bolas, Sea Gate Oracle, Mulldrifter.
Note with Mulldrifter that you can pay the evoke cost and then while the trigger is on the stack then cast a target spell on it so that you get a copy before you sacrifice. That way you get a permanent copy (token) in play that you can then use for further targeting.
There are some that allow you to search your library for various cards.
With Spellseeker you can keep getting further cards to make copies. There are 21 instant or sorcery spells that can copy the Spellseeker so in theory you can keep looping these to make an army of them.
However 1/1 is not an impressive stats even though you can literally put 22 of them onto the board.
Trinket Mage can get more artifact mana.
Kaho, Minamo Historian is great because it can get you instants and then when you have used all 3 you can then copy Kaho, Minamo Historian to create a new version and search for more. You can keep looping value because the last instant you search for can be another targeting spell to specifically target Kaho meaning you'll get at least 2 instants for additional value each cycle.
Solemn Simulacrum is more land ramp and of course a great creature to copy as you can get draw on death.
There are ways to cast or retrieve from graveyard in;
Snapcaster Mage, Torrential Gearhulk, Scholar of the Lost Trove, Archaeomancer, Shipwreck Dowser.
Torrential Gearhulk and Scholar of the Lost Trove represent potentially mid-late game finishers.
Given that you can keep making copies of them for as many targeting creature cards as you have in graveyard it is easy to create an army of them.
Torrential Gearhulk is specifically instants but that is still most of them as there are only 6 sorcery targeting cards.
Scholar of the Lost Trove can also target sorcery and the flying is nice as well.
Going back to the Spellseeker you can see that a mighty game plan is to simply filter through as many instant and sorcery from your library as possible to put into your graveyard and then cast Torrential Gearhulk or Scholar of the Lost Trove to easily put more than enough attackers onto the board to kill opponents pretty quickly.
Archaeomancer and Shipwreck Dowser can get back any instant or sorcery so you can keep looping copying it to make more copies.
If you are specifically using a draw type effect as well then it means that you can keep drawing cards.
A classic example would be to keep getting back say Cerulean Wisps and copying the Archaeomancer.
You get an additional 1/2 and draw a card for every you have, which is pretty amazing value given that you can just keep doing this every turn.
Shipwreck Dowser is a lot better in that it's a 3/3 body with prowess that can set up lethal attacks actually pretty quickly. Think Monastery Mentor type antics.
Snapcaster Mage is similar but exiling your instant or sorcery does mean that you can't loop the same way, but you can still get great value.
Peregrine Drake is a nice way to unlock your mana which can be super important to efficient turns.
You can actually get infinite mana with any buyback spell that targets a creature and costs 4 or less which are Whim of Volrath
Mind Games, Clockspinning.
Gilded Drake can be copied while the trigger is on the stack so you can look to steal multiple creatures depending on how many targeting spells you have and how much mana you have available.
Glen Elendra Archmage is just a nice creature to copy for the sake of countering spells. Turning all your targeting spells into non-creature counters is pretty much a soft-lock.
Changeling and Wizards
A few little advantages you can get from the fact that Orvar, the All-Form is a changeling is that Aquitect's Will, Chilling Trap and Stream of Unconsciousness means that you have a Wizard and a Merfolk for the draw triggers.
Cavern of Souls and Path of Ancestry also work nice with Orvar, the All-Form being a changeling.
You can name Wizard with Cavern of Souls which 2/3 of the creatures in the deck are.
Riptide Laboratory can be used to return a Wizard and you can look to use it to protect Orvar, the All-Form when you can.
Swarmyard is another land that you can look to protect Orvar, the All-Form as he is all of those creatures.
Color me..
A nice little interaction is using the cards that change color words in Trait Doctoring, Whim of Volrath, Glamerdye, Crystal Spray can be used to alter Insight and Hydroblast to make them more effective.
Changing Insight to a more popular color in the game will also create another version of the card although it will default to Green as the copy is a cast trigger so would happen before the color change happens. However there is normally one or two Green color-pie inclusive mages at a table anyway.
Hydroblast can actually target any permanent for Orvar, the All-Form trigger and obviously also good against Red decks.
In a pinch you can use one of the color changing cards to turn it into a hard counter.