Quote from"Saproling" seems to be a generic term for small plant/fungus creatures rather than a specific species.
Indeed what a Saproling is varies from plane to plane - sometimes even within a plane; on Ravnica in the old days Saprolings differed from guild to guild; Selesnya Saprolings are small creatures consisting of vines wrapped around crystals (as can be seen in the artwork) - the vines are based on plants which is why the Selesnyan Saprolings use seeds and pollen; Golgari Saprolings with the guilds focus on lightless subterranean rotfarms are classical fungal beings; Simic Saprolings are open to interpretation, though they are cyan/green-blue globules and seem to consist entirely of their trademark Cytoplast.
Guildless Saprolings could follow either style guide or none at all.
Remember: A Saproling doesn't need to be fungal. If anything its root tells us more about the fact that it likes death and decay. It can be (and sometimes is) a plant and apparently sometimes part gem.
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Now you don't only seem to have a problem with Saprolings being not depicted fungal enough, but with Saprolings depicted too much like a Fungus. For example the "earthstars" are not there for there own sake. Those are the Saprolings that Vitaspore Thallid tosses around. Look at the mechanic and art and tell me that "every now and then it throws a new creature onto the field" isn't what the Thallid mechanic is actually reads like.
You can see similar depictions of Saprolings on Thallid cards again and again e. g. a big "white" Thallid in front of a few smaller "green" Saprolings on Pallid Mycoderm; maybe now you also understand the boring palette of colors: When an artist gets told to paint a "green" Fungus it will end up being green more often than not.
Creature - Human Ninja
Level up :1mana::symu: [2/2]
[1-3] Whenever Ninja of the Deep Hours deals combat damage to a player, you may draw a card. [3/3]
[4+] Whenever Ninja of the Deep Hours deals combat damage to a player, you may draw up to four cards. [4/4]
Next: Battle Rampart
Tribal Sorcery - Sand
Destroy target land. If a nonbasic land is destroyed this way, put two 1/1 colorless Sand creature tokens onto the battlefield.
Next: Rib Cage Spider
Creature - Human Mystic
~ gets +1/+1 for each enchantment you control.
Enchantments you control have shroud.
1/1
Artifact - Equipment
Equipped creature gets +0/+2 and has reach.
Equip
Next: Giant Spider
Instant
Exile target spell. It deals damage to its controller equal to its converted mana cost.
Next: :symg::symu:
Creature - Reflection
Flash
Whenever a creature is put into a graveyard from the battlefield, you may have ~ become a copy of that creature. It gains this ability.
2/2
Next: Tarkatan Warrior
Creature - Fungus Beast
Lifelink, trample
At the beginning of your upkeep, ~ deals 1 damage to each other creature.
6/6
Next: :symg::symu:
Creature - Insect
:2mana:, Sacrifice a land: ~ gets +3/+3 until end of turn. Activate this ability only once each turn.
3/3
Tribal Enchantment - Hydra Aura
Enchant creature
Enchanted creature can't be blocked except by a number of creatures equal to the number of +1/+1 counters on it or more.
:1mana::symg:: Put a +1/+1 counter on enchanted creature.
Card Type: Tribal
Next: Illusion (Imp, Incarnation, Insect)
It's from twitter, so good luck finding a link.
Further there has been only a single multicolored planeswalker last block, so there is no precedent outside of Alara - the gold block.
Anyway, I suspected Tezzeret going UB anyway - and with him not appearing early it is even more likely since the later sets in the block will probably have a stronger Phyrexian presence.
On the other hand the case would be stronger if Venser would have been mono-blue and Tezzeret wouldn't have been implied as fighting Phyrexia.
Siding with Bolas still makes a good case for more black anyway.
Creature - Spirit Mystic
Whenever ~ attacks, the defending player puts the top four cards of his or her library into his or her graveyard.
:symb:, Exile a creature card from a graveyard: Regenerate ~.
2/1
Tribal Enchantment - Horror
Creatures you control get +2/-2.
Card Type: Tribal
Next: Horse
Artifact (mythic)
Whenever ~ or another artifact enters the battlefield under your control, put a -1/-1 counter on target creature, then proliferate.
:4mana:, Tap an untapped artifact you control: Proliferate.
CALL: Rusalkas for artifacts rather than creatures.