I flipped the image with four cards. The upper left normal image corresponds to the lower right flipped image. I know, this is just as confusing as the flip cards... it would have been a lot more time to flip each image individually.
Here are the white ones.
1. Bushi Tenderfoot to Kenzo the Hardhearted: you have to deal damage to another creature and not have Bushi die, then you can flip it. This will likely require a battle trick card since as a 1/1, Bushi isn't much of a threat. With a green 'this creature fights this other creature' you can do it, but you would need to enchant Bushi to buff it up. This is too much work, a temporary buff sounds a lot easier. Kenzo is pretty good, but it has to be blocked to get buffed with Bushido. Enchanting Bushi from the get-go is what I should try.
2. Rune-Tail, Kitsune Ascendant to Rune-Tail's Essence: Rune-Tail has a Felidar Sovereign deck in its future. This flipping condition is not difficult to attain in a deck dedicated to life gain. I really like this flip condition, a conditional Fog for your creatures... very nice!
3. Faithful Squire to Kaiso, Memory of Loyalty: It belongs in a Spirits and Arcanes deck. The flip condition seems fair: play two Spirits or Arcanes, collect two ki counters, then flip. It only gets two ki counters, therefore can protect two times, really like regeration twice. Its not bad, but not super good either.
4. Kitsune Mystic to Autumn-Tail, Kitsune Sage: This one is easy to flip. Its a four-drop and by the time you can cast it it will be easy to have he two auras you need. It fits with Bushi. A one drop cost to play Aura chenanigans sounds like a lot of fun, but this isn't something that you want to be doing a lot. Usually you will want to place an Aura on the best creature for it and leave it there. Now, if someone targets an Aura for destruction, does it work to move it to save it? Must try.
Here are the blue ones. Erayo was $5... ouch, that's an expensive rental.
1. Erayo, Soratami Ascendant to Erayo's Essence: This is one easy flip condition. This card was made for multi-player, where four spells cast in a turn should happen all the time. I would add all the Surge cards out of OGW. After you flip, you are countering all opponent's first spell... wow, that's worth a $5 rental all-right.
2. Jushi Apprentice to Tomoya the Revealer (2/3, does not show is my screen capture): I so not like the 'cards in hand' thing. The point of playing this game is to cast spells. Still, if I wanted to see this flip happen, I will need Reliquary Tower to have a hand larger than seven cards. The cost to draw a card each turn is reasonable, and if we add an Aura to unflip it, such as Crab Umbra, we can use this effect more than once per turn late game. Also, see Freed from the Real, Aura of Dominion, but the easiest one is Magewright's Stone-an artifact. This flip effect is a lot of work.
OK, I flipped it, now what? Oh... ok, I see the benefit. This thing is card drawing madness. I am sold!
3. Student of Elements to Tobita, Master of Winds (3/3, does not show is my screen capture): I would enchant it to give it flying. It fits in the white Aura theme I discussed with the white flip cards. Its an easy flip to cause, and giving Flying to all of your creatures is great. I would put it with a bunch of green breaters and make them all flyers.
4. Callow Jushi to Jaraku the Interloper: Two castings of Spirits or Arcanes for the two ki counters to flip: seems doable. For the flip you get two casts of something like a Mana Leak but making your opponent pay 2 instead of 3. Not bad, but late game your opponent will likely have the mana to pay. Its worth a try.
1. Nezumi Graverobber to Nighteyes the Desecrator: You will need to either have one creature in your opponent's graveyard and exile it, or do the exiling and then exile the rest of their graveyard.
I really like this flip result. This is a lot of reanimation fun!
2. Nezumi Shortfang to Stabwhisker of the Odious: Its great to get your opponent to have no cards in hand, and there are many other cards that can help you do this in a few turns. It happens to me often enough to annoy me! The life loss condition is not fantastic since your opponent can have three or more cards in hand and not pay any life to this effect. Still, the before-flip benefit is so good,
that I would not care much for collecting the benefit of the flip.
3. Hired Muscle to Scarmaker: Another 'two or more ki counters' effect. By now we have seen the same effect in white and blue. That means we can do ki counters in Esper and
use a reanimator shell with my favorite card from this block, Gifts Ungiven. You get Fear twice, which is great against decks without black.
4. Kuon, Ogre Ascendant to Kuon's Essence: Fits in a black/green 'sacrifice creature' sacrifice shell. Sacrificing three creatures requires a lot of work, yet I like the temporary black devotion of three. The flip effect can be great against some decks, but in Modern, a dud against low creature or no-creature decks, which are common enough.
2. Akki Lavarunner to Tok-Tok, Volcano Born: Its hard to pull off this effect on a four-drop. You will need a card to make it unblockable, either one time, or as an Aura. When flip, it fits as a finisher in Red Deck Wins, and it even protects for the mirror. Of course, we know that there are many cards that are better in this slot for Red Deck Wins. Still worth trying.
3. Initiate of Blood to Goka the Unjust: You will either have to hit a 1/1 or hit it with something else to make sure the opposing creature dies. This is a four-drop. The best way to pull this effect off is for the 1 damage to be coupled with other damage, which will often mean that the 1 damage will
not be needed to kill the creature. After the flip, you can take out creatures with toughness 4 or less one by one, which is useful against the right deck, and not useful against many decks in Modern. This card has narrow use.
4. Homura, Human Ascendant to Homura's Essence: Its a whopping 6 drop... I will usually stop there and move on. It is easy to flip, since you can pair it with block and kill it with a myriad of black target removal cards. The flip better be good: ok, that's good. Its not earth-shattering, but +2/+2 and makes all your creatures flyers is very good. This card does not win you the game alone, but its worth trying just to learn how it works.
1. Budoka Gardener to Dokai, Weaver of Life: The effect seems really good, but additional land effects can be fickle. You have to have that additional land in your hand. Still, more mana is great.
The flip effect is great, though. It reads game-ending. I like it a lot.
2. Orochi Eggwatcher to Shidako, Broodmistress: To control ten or more creatures earlier in the game you will need to drop a lot of them early. Its not an elf, and it is in an elf deck where you can do this the easiest. The next candidate is coupling with white or red and using the token droppers available in those colors. A white/red/green, or Naya, shell is called for. Once flipped, its cheap to buff one of your creatures, and it can be used as a battle trick. Sacrificing requires black... that's four colors already. Maybe an Abzan (white/black.green) shell then since Abzan has gotten many cards added in Khans of Tarkir block.
3. Budoka Pupil to Ichiga, Who Topples Oaks: Another 'two or more ki counters' effect, one in each color. The counter gain seems minuscule at +2/+2 but if you are running a lot of Spirits and Arcanes its basically a free effect.
4. Sasaya, Orochi Ascendant to Sasaya's Essence: Another 'big hand' effect. It goes well with Budoka Gardener and Jushi Apprentice. I really like this flip effect: if you pull it off, you will be swimming in mana. Mono-green seems the best pool to try this effect in.