54 cards where the text includes “toxic” and (the card is available on Paper) and it’s legal in Standard

Annex Sentry (Phyrexia: All Will Be One #2)
Aspirant's Ascent (Phyrexia: All Will Be One #40)
Basilica Shepherd (Phyrexia: All Will Be One #4)
Bilious Skulldweller (Phyrexia: All Will Be One #83)
Blightbelly Rat (Phyrexia: All Will Be One #85)
Bloated Contaminator (Phyrexia: All Will Be One #159)
Branchblight Stalker (Phyrexia: All Will Be One #160)
Charge of the Mites (Phyrexia: All Will Be One #6)
Compleat Devotion (Phyrexia: All Will Be One #7)
Crawling Chorus (Phyrexia: All Will Be One #8)
Duelist of Deep Faith (Phyrexia: All Will Be One #9)
Dune Mover (Phyrexia: All Will Be One #226)
Flensing Raptor (Phyrexia: All Will Be One #12)
Goliath Hatchery (Phyrexia: All Will Be One #408)
Hexgold Slash (Phyrexia: All Will Be One #137)
Ichorspit Basilisk (Phyrexia: All Will Be One #170)
Indoctrination Attendant (Phyrexia: All Will Be One #16)
Infested Fleshcutter (Phyrexia: All Will Be One #17)
Jawbone Duelist (Phyrexia: All Will Be One #18)
Karumonix, the Rat King (Phyrexia: All Will Be One #98)
Kinzu of the Bleak Coven (Phyrexia: All Will Be One #406)
Lukka, Bound to Ruin (Phyrexia: All Will Be One #207)
Maze's Mantle (Phyrexia: All Will Be One #174)
Mirrex (Phyrexia: All Will Be One #254)
Mite Overseer (Phyrexia: All Will Be One #404)
Monument to Perfection (Phyrexia: All Will Be One #233)
Myr Convert (Phyrexia: All Will Be One #234)
Necrogen Communion (Phyrexia: All Will Be One #99)
Necrogen Rotpriest (Phyrexia: All Will Be One #212)
Nimraiser Paladin (Phyrexia: All Will Be One #101)
Paladin of Predation (Phyrexia: All Will Be One #178)
Pestilent Syphoner (Phyrexia: All Will Be One #103)
Plague Nurse (Phyrexia: All Will Be One #179)
Porcelain Zealot (Phyrexia: All Will Be One #30)
Prosthetic Injector (Phyrexia: All Will Be One #239)
Ria Ivor, Bane of Bladehold (Phyrexia: All Will Be One #214)
Ribskiff (Phyrexia: All Will Be One #240)
Sheoldred's Headcleaver (Phyrexia: All Will Be One #109)
Skrelv, Defector Mite (Phyrexia: All Will Be One #33)
Skrelv's Hive (Phyrexia: All Will Be One #34)
Slaughter Singer (Phyrexia: All Will Be One #216)
Stinging Hivemaster (Phyrexia: All Will Be One #110)
Tainted Observer (Phyrexia: All Will Be One #217)
Toxic Abomination (Dominaria United #112)
Toxic Scorpion (Innistrad: Crimson Vow #224)
Tyrranax Atrocity (Phyrexia: All Will Be One #188)
Tyrranax Rex (Phyrexia: All Will Be One #189)
Unctus's Retrofitter (Phyrexia: All Will Be One #76)
Venerated Rotpriest (Phyrexia: All Will Be One #192)
Venomous Brutalizer (Phyrexia: All Will Be One #193)
Venser, Corpse Puppet (Phyrexia: All Will Be One #219)
Viral Spawning (Phyrexia: All Will Be One #194)
Voidwing Hybrid (Phyrexia: All Will Be One #221)
White Sun's Twilight (Phyrexia: All Will Be One #38)

Though this query has ended, its relics still slumber in New Argive.