Mystic Reflection is an incredibly good card that I think many are sleeping on. It can act as:

1) Removal (turning your opponent's entering creature into something weak, like a 1/1 Pest token)

2) Copy the best thing your opponent controls (for when you're behind)

3) Copy the best thing you control (for when you're ahead)

But wait, it gets better! The value of this card sky rockets if you can make multiple creatures enter the board at the same time: now you're getting two (or more!) copies of the best thing on the board.

And already we have an easy two card combo with Tovolar's Huntmaster // Tovolar's Packleader: cast Tovolar and let the spell resolve. Then, while the ETB trigger is on the stack, cast Mystic Reflection targeting Tovolar, and boom: for 7 mana you just made three 6/6 creatures with upside and four 2/2 Wolf tokens. But wait, the combo gets even easier; what if you've already cast Tovolar? Not to worry, because when he flips to his nightbound side he can also attack to create two creature tokens, allowing you to combo off if you drew your Mystic Reflection later, or if you really just needed three creatures on the board on turn five to help you stabilize and couldn't wait an additional turn for that extra mana.

And this isn't even the best combination with this card, not by far. Here's the second namesake of the deck:

Maybe you can see where this is going... now instead of making two of the best creatures on the board, we're making many more than that: often four copies, or six... or sometimes even ten+ copies (if you combo these cards off with Wrenn and Seven's treefolk token). Awesomely, Tend the Pests is an instant speed spell, allowing you to get this combo off on your opponent's turn.

This is a spike midrange deck, not a jank combo deck

However, don't be deceived, this is not an actual combo deck. Both Mystic Reflection and Tend the Pests are very good cards in the deck even when you're not combo-ing. Mystic Reflection often gets enormous value by turning something stupid of yours, like an Eyetwitch, into something else on the board, say a Titan of Industry that your opponent has played. For 2 or 3 mana, copying the best thing on the board is huge value.

And Tend the Pests is excellent against aggro. Once you are able to make large power creatures like Topiary Stomper, you can hold up Tend the Pests as a response to the inevitable removal spell from your opponent. Now you have 4 or more chumpers that gain you life when they die, and you also might have gained a bunch of life if you happened to have a Prosperous Innkeeper on the board.

This flexibility is what makes this deck strong, particularly against the very fast meta we are in where opponents can pressure your life total quickly.

Play it as Midrange, not as Combo (aka, this deck is not for gamblers)

My advice to anyone wanting to play this deck is to play these cards when they have good value, and DON'T wait until you've assembled the perfect combo. It's easy to think, "if I just cast Memory Deluge and find the Tend the Pests, this Mystic Reflection gets even better," and in the process of hunting for that perfect combo, you miss out on many good plays.

I can't stress this enough, despite the tag I put on this decklist, this is NOT actually a combo deck, or if it is, it is a bad combo deck. Good combo decks will win the turn that they play the combo. This can rarely do that. It can't even reliability do that the turn after you play the combo. Instead, this is a Midrange deck. So play it that way, including playing your "combo" cards like Mystic Reflection and Tend the Pest when they have good value, or when they may be critical to stabilizing the board, rather than waiting to assemble a "game winning" combination.

High IQ play patterns and non-obvious combos/synergies

• When Tovolar's Huntmaster // Tovolar's Packleader is on his Nightbound side, copies of him are permanently on their Nightbound side, even when it flips to Day, because copies of cards cannot transform. The reverse is also true, and a copied daybound creature will always stay daybound. Ideally you want to copy Tovolar on his nightbound side if you can.
• If you have Tend the Pests and Mystic Reflection in hand and are ready to combo off with a Tovolar, you can choose to do this on your opponent's turn instead. Cast no spells on your turn so Tovolar will flip to his night side. Put a stop on your opponent's upkeep and get the combo off on their turn. Obviously, you should be cautious of doing this if you fear ineraction from your opponent.
• An incredibly savvy opponent can screw with your combo if they have an instant speed way to make a creature: with Mystic Reflection resolved and while all your tokens are on their way to enter the field, your opponent can instant speed create their own creature, which will now enter as a copy from Mystic Reflection. You're left over with a bunch of weak, non-copied tokens and they now have a copy of the best thing on the board. If you suspect your opponent has an instant speed way to make creatures, consider playing around this trick.
• If your opponent has exiled multiple of your creatures with one or more of their Brutal Cathar // Moonrage Brute, a board wipe will allow you to get multiple creatures to enter the field at once... this can combo off with Mystic Reflection if you can destory them with, say, a Meathook Massacre.
• Pest Summoning can be retrieved from your learn-board to give you a low-mana cost way to make two creatures enter the battlefield at once. Likewise, Mascot Exhibition can be pulled from your learn-board to make three creatures at once.
• Mystic Reflection can be used to sort-of-counterspell an opponent's planeswalker, since it also makes the next planeswalker enter as a copy of something. Say your opponent casts a Blood on the Snow. In response, cast Mystic Reflection on your own Eyetwitch and now their Lolth, Spider Queen will enter as a 1/1 flyer instead. Beautiful.
• Prosperous Innkeeper can be an excellent target for the combo. Say you have a 7/7 treefolk token made by Wrenn and Seven. Comboing off with Tend the Pests and Mystic Reflection will net you 7 times 6 life, because each Innkeeper will "see" the other Innkeepers enter, gaining you a total of 42 life and creating 7 treasure tokens to boot. Copying Innkeeper will gain you N * (N-1) life, where N is the number of copies you are making.

Good targets from an opponent:

• Righteous Valkyrie is an incredibly good target, as I discovered in a game I feature in my deck tech video: if you can make even just a few copies of Righteous Valkyrie, the effect is literally exponential: they all trigger each others' life gain, almost certainly getting you up to that magic 27 life, at which point they all also pump each other by +2/+2 for each copy, and the remaining life gain triggers on the stack now gain you even more life. The end result is you will have some huge creatures and an incredibly high life total. In the deck tech video, I was able to get more than 1,000 life with this!
• Brutal Cathar // Moonrage Brute as a copy target can help you wipe the board, even when you're just making two copies, often times also getting you back an additional creature by using one of your new Brutal Cathar // Moonrage Brute to remove their Brutal Cathar // Moonrage Brute and so returning one (or more) of yours from exile.
• Haste creatures are very good targets and can allow you to win the game immediately after combo: Goldspan Dragon, Bloodthirsty Adversary, Thundering Raiju, etc.
• Bloodthirsty Adversary as a target can allow you to combo off twice in one turn, if you've managed to retain two treasure tokens from Prosperous Innkeeper to make some red mana. Here's how it works: Make two copies of their Adversary, then you can pay the extra six mana to copy Mystic Reflection and Tend the Pests from the graveyard, doing the combo immediately a second time! If you have no other high power creatures, make sure you pay the cost twice from the same Bloodthirsty Adversary: this will grow it's power to 4, allowing you to combo off to make 4 additional copies of something.