Histogram version, by rounded GIHWR
60 🔵
59 🔴⚪🔵🔵⚪
58 ⚪🔵🔴🔵⚪⚪🔴🟡
57 ⚪⚪🟤🔵🟢⚫⚫🟤⚪🔴🟢🟢🟢
56 ⚪🔵⚪🟢🔘⚫🟤🟡🟡🟤🟡🟤🟤
55 🟤🟢🔘⚫⚫🟡🟤🟢🔵🟢🟤⚫🔴🟡
54 🟤⚪🔵🔵⚫⚫🟡🔴🟡🔘🟤🔘⚫🔴
53 🔵🔵🟢⚫⚪🟡⚪🔴🔴🟢🟡⚫🔴⚫
52 🔴🟢🔵⚫🔴🟢
51 🔴
50 🟢
49 🔘

𝐀𝐦𝐛𝐢𝐯𝐚𝐥𝐞𝐧𝐜𝐞 {1}{B}{R}
Creature -- Elemental
When ~ enters, choose one —
• ~ deals 3 damage to target creature.
• Target creature gets -0/-3 UEOT.
3/1

𝐁𝐨𝐧𝐡𝐨𝐦𝐢𝐞 {2}{W}{W}
Creature -- Elemental
Tapped creatures you control get +1/+1 for each untapped creature you control.
Untapped creatures you control get +1/+1 for each tapped creature you control.
2/2

𝐙𝐞𝐢𝐭𝐠𝐞𝐢𝐬𝐭 {3}{W}{B}
Creature -- Elemental Spirit
Flying
At the beginning of each phase, put a +1/+1 counter on ~.
At the beginning of your end step, remove all counters from ~.
1/1

𝐏𝐞𝐫𝐬𝐩𝐢𝐜𝐚𝐜𝐢𝐭𝐲 {2}{U}{U}
Creature -- Elemental
Flash
When ~ enters, return target spell or creature to its owner's hand.
Plot {2}{U}
1/2

A little @scryfall.com searching has turned up this card, which is new to me. A little on the expensive side, but it definitely plays the role of "play me after you've cast a million cheap spells."

Electrostatic Infantry, at 2mv (with Trample!) might be cheap enough to work...

Surely one of the *-powered flyers or the Infantry -- or something like them -- could be printed at common.

Right?

...these all want you to wait until you've cast the creature before you really start slinging.

Tolarian Terror works because you can fire off a bunch of spells early and they all just make the Terror better. Same goes for things like Enigma Drake/Spellheart Chimera...

This is apparently just how divided in half is shown on German cards.

Link here: www.reddit.com/r/magicTCG/c...

I'm sure you can explain why many of these are non-bos, but some of them seem like surprising omissions!

* "never appeared" as intrinsic abilities -- so this excludes cards that can gain these abilities, including by "borrowing" them:
tagger.scryfall.com/tags/card/bo...

* For those who need it spelled out: creatures for {M}{N} that do exactly The Thing that the color pair wants to be doing, across essentially all sets and contexts.