I'm using the promo with Ice Age art, but for non-foils Mirage is probably my favourite.
I'm on basically maximum single target removal power level. I'll diversify if the power level drop isn't too large, but I'll generally play the better version of the same effect.
I like that efficient removal puts more emphasis on curve and that it punishes decks that don't have a clear gameplan. It does help removal.deck, but I've found 2 for 1 removal is much more important than stuff like Lightning Bolt for those decks.
I don't think I've ever seen Disfigure used as a combat trick. There are just so few creatures bigger than a x/2 outside of green, and having to get both one on each side and have them fight is rare (not to mention getting blown out).
Fungal Infection is disfigure + a 1/1 if you have a decent x/1 target, which is a huge upside on a 1 cmc spell. It can also 2 for 1 defensively against 2 x/1s, and it can be a combat trick (2/2 vs. 2/2 happens way more than 3/3 vs. 4/4). I'm not saying it's an auto include, but it's a flexible card with a solid average case and a good ceiling.
I'm planning to include Fungal Infection. Over a third of my creatures are x/1s, most decks make good use of 1/1s, and it's a pretty reasonable defensive trick. I think it's a solid choice for B cost removal: Disfigure has a low ceiling, Tragic Slip is hard to turn on at times, Darkblast is match-up specific, and Fatal Push has its limitations.
The only theoretical deck where Final Parting looks good to me is where it gets Unburial Rites + Pelakka Wurm/Trostani's Summoner. Outside of that it's either too low tempo or too low value.
Warcry Phoenix costs 1 too much on either cost or is missing a point of power. Too expensive for aggro and not worth the effort elsewhere.
I have 6 first strikes for Kwende, Pride of Femeref; I thought I had about double that and was still questioning how playable it was. Really fragile without a great ceiling.
I think Garna, the Bloodflame has a decent enough average case, though in low econ situations it's not a great top deck. 3/3 is a relevant body, haste is a relevant effect, and getting a creature to die isn't too difficult. Having flash + giving haste also gives pseudo protection for stuff on board. You can also sac it with the trigger on the stack for infinite value.
Whisper, Blood Liturgist needing 2 activations in most cases to be good is just too slow. Works excellently with 2+ token makers, but there just aren't a ton of those.
I'm not sold on Adventurous Impulse. It's decent when you need lands, but it's pretty mediocre when you need creatures. In a 15 creature deck it doesn't hit a creature 23% of the time and 46% of the time you don't get a choice of creatures; you only get card selection 31% of the time.
Dauntless Bodyguard is obviously great. Well stated card with the ability being potentially game winning on something like Blood Artist.
I like that Adeliz, the Cinder Wind has a better fail case than Stormchaser Mage, but it's not exciting. Siren Stormtamer -> Stormchaser Mage -> Adeliz -> Spells is a pretty great curve, but their are so few other aggressive wizards.
Using Song of Freyalise's 1-2 ability effectively seems difficult in most decks. The 3 ability looks pretty ridiculous, but these effects always look better than they are.
As much as I like incidental lifegain, Tatyova, Benthic Druid doesn't really appeal to me. 5 drops with minimal immediate impact aren't where I want to be. At a 3/5 I could see Tatyova being solid, but not at 3/3.
I remember seeing a big drop off for guild cards after the 6th card for most guilds, where the cards got to being barely better than mediocre monocoloured cards, but we've gotten a number of good guild cards since then. I feel pretty comfortable at 6, with most of the cards I want to replace being more boring than weak.
Guild cards do end up clogging the back end of packs, so you do have to determine whether you value the extra playables or more interesting cards.
2/2 first striker is pretty poor when not against aggro; most of the time she's probably too low impact for a three drop. If you're supporting pants then go nuts, but otherwise she seems pretty mediocre.
Why does Triumph of Gerrard only target highest power? It could be vaguely interesting if there were no targeting restrictions.
If you're trying to support multiple 3 colour decks then you probably want a bit higher than ~25 fixers, but other than that guild cards don't really require much more fixing than normal.
I think a lot of people value playable count pretty highly, thus low numbers of guild cards.
I'm on basically maximum single target removal power level. I'll diversify if the power level drop isn't too large, but I'll generally play the better version of the same effect.
I like that efficient removal puts more emphasis on curve and that it punishes decks that don't have a clear gameplan. It does help removal.deck, but I've found 2 for 1 removal is much more important than stuff like Lightning Bolt for those decks.
Fungal Infection is disfigure + a 1/1 if you have a decent x/1 target, which is a huge upside on a 1 cmc spell. It can also 2 for 1 defensively against 2 x/1s, and it can be a combat trick (2/2 vs. 2/2 happens way more than 3/3 vs. 4/4). I'm not saying it's an auto include, but it's a flexible card with a solid average case and a good ceiling.
Dauntless Bodyguard - 1 mana 2/1s are typically boring, but not this one.
Cast Down - Will hit 97% of creatures post update.
Test and expect to be good:
Memorial to Glory - Good White spell land. A lot of decks want tokens too.
Tetsuko Umezawa, Fugitive - Pretty powerful effect, though narrow.
Garna, the Bloodflame - Interesting enough to test; a Fires effect on a flash body doesn't need too much more to be good.
Merfolk Trickster - UU is a bit harsh, but Snakeform with a better floor is nice
Saproling Migration - Solid token maker.
Untamed Kavu - Versatile threat, though boring.
Fungal Infection - Really efficient card, though a bit high variance.
Testing and expecting to be mediocre:
Grunn, the Lonely King - Person in my playgroup likes to try to 1 shot with Psychatog.
Baird, Steward of Argive - 1 mana is not 2 mana, though it is interesting enough.
Shanna, Sisay's Legacy - 2 mana leads to more curve outs than similar cards.
Other:
Fight with Fire - Probably playable, but I don't want to specifically encourage 9 land gameplans.
Song of Freyalise - Super high variance Overrun.
Song of Keld - I'm tempted, but I will restrain myself.
Fungal Plots - Ongoing Investigation this is not.
Warcry Phoenix costs 1 too much on either cost or is missing a point of power. Too expensive for aggro and not worth the effort elsewhere.
Untamed Kavu is solid.
I have 6 first strikes for Kwende, Pride of Femeref; I thought I had about double that and was still questioning how playable it was. Really fragile without a great ceiling.
I think Garna, the Bloodflame has a decent enough average case, though in low econ situations it's not a great top deck. 3/3 is a relevant body, haste is a relevant effect, and getting a creature to die isn't too difficult. Having flash + giving haste also gives pseudo protection for stuff on board. You can also sac it with the trigger on the stack for infinite value.
Whisper, Blood Liturgist needing 2 activations in most cases to be good is just too slow. Works excellently with 2+ token makers, but there just aren't a ton of those.
Slinn Voda, the Rising Deep is way too expensive, though Crystal Shard + 11 mana does sound real appealing with it.
Grunn, the Lonely King is pretty sweet: Temur Battle Rage is a one shot, Fires of Yavimaya gives haste and buffs, Rancor is a ton of damage, etc.. Might put it in as a combo card.
Baird, Steward of Argive is pretty narrow, though it does fill its role really well.
I like that Adeliz, the Cinder Wind has a better fail case than Stormchaser Mage, but it's not exciting. Siren Stormtamer -> Stormchaser Mage -> Adeliz -> Spells is a pretty great curve, but their are so few other aggressive wizards.
Using Song of Freyalise's 1-2 ability effectively seems difficult in most decks. The 3 ability looks pretty ridiculous, but these effects always look better than they are.
As much as I like incidental lifegain, Tatyova, Benthic Druid doesn't really appeal to me. 5 drops with minimal immediate impact aren't where I want to be. At a 3/5 I could see Tatyova being solid, but not at 3/3.
Guild cards do end up clogging the back end of packs, so you do have to determine whether you value the extra playables or more interesting cards.
Why does Triumph of Gerrard only target highest power? It could be vaguely interesting if there were no targeting restrictions.
I think a lot of people value playable count pretty highly, thus low numbers of guild cards.
Manaplasm
Experiment One
Augury Owl
Victimize
Smoldering Werewolf
Psychatog
Possessed Skaab
Unburial Rites