Breath of the Sleepless 
Enchantment
$0.28 #14654 0.12 4.8 years
You may cast Spirit spells as though they had flash.
Whenever you cast a creature spell during an opponent's turn, tap up to one target creature.
Click a line or tag to filter
Cards similar to Breath of the Sleepless expected a card that isn't here?
Reports become test cases the matcher is graded against before an update ships. Delvefall isn't a chatbot guessing, it compares the printed rules text of every card with plain math, and examples like yours decide which differences should count.
Rattlechains90%
$0.35↑#10438↑0.25↑10.4 years↑
"You may cast Spirit spells as though they had flash."
Supernatural Rescue80%
$0.10↓#24805↓0.34↑4.8 years
"When you cast this spell, tap up to two target creatures you don't control."
+1 more matching line
Elite Skirmisher79%
$0.15↓#27098↓0.00↓12.6 years↑
"Whenever you cast a spell that targets this creature, you may tap target creature."
Onslaught78%
$0.15↓#21633↓0.30↑28.2 years↑
"Whenever you cast a creature spell, tap target creature."
Wavecrash Triton76%
$0.13↓#26426↓0.1812.9 years↑
"Whenever you cast a spell that targets this creature, tap target creature an opponent controls. That creature doesn't untap during its controller's next untap step."
High Fae Trickster76%
$4.67↑#870↑0.37↑1.8 years↓
"You may cast spells as though they had flash."
Innocence Kami76%
$0.19↓#29377↓0.0721.9 years↑
"
, 
: Tap target creature."
, : Tap target creature."+1 more matching line
Dream Spoilers76%
$0.15↓#19257↓0.123.0 years↓
"Whenever you cast a spell during an opponent's turn, up to one target creature an opponent controls gets -1/-1 until end of turn."
Quiet Contemplation74%
$0.21↓#18701↓0.88↑11.9 years↑
"Whenever you cast a noncreature spell, you may pay 
. If you do, tap target creature an opponent controls and it doesn't untap during its controller's next untap step."
. If you do, tap target creature an opponent controls and it doesn't untap during its controller's next untap step."
D'Avenant Trapper74%
$0.05↓#23376↓0.208.4 years↑
"Whenever you cast a historic spell, tap target creature an opponent controls."
Dreamspoiler Witches74%
$0.26↓#23206↓0.29↑18.9 years↑
"Whenever you cast a spell during an opponent's turn, you may have target creature get -1/-1 until end of turn."
Nightmare Sower73%
$0.22↓#132950.00↓0.6 years↓
"Whenever you cast a spell during an opponent's turn, put a -1/-1 counter on up to one target creature."
Glen Elendra Pranksters72%
$0.31↑#18014↓0.32↑18.9 years↑
"Whenever you cast a spell during an opponent's turn, you may return target creature you control to its owner's hand."
Harrier Griffin72%
$0.12↓#25434↓0.33↑20.6 years↑
"At the beginning of your upkeep, tap target creature."
Leyline of Anticipation72%
$3.40↑#735↑0.56↑16.1 years↑
"You may cast spells as though they had flash."
Sentinel of the Eternal Watch72%
$0.12↓#169820.0611.1 years↑
"At the beginning of combat on each opponent's turn, tap target creature that player controls."
Borne Upon a Wind72%
$4.91↑#650↑0.46↑3.2 years↓
"You may cast spells this turn as though they had flash."
Captain Mar-Vell, Space-Born72%
$0.12↓#167560.00↓0.2 years↓
"As long as an opponent has cast a spell this turn, you may cast spells as though they had flash."
Kami of the Hunt71%
$0.09↓#28030↓0.25↑21.9 years↑
"Whenever you cast a Spirit or Arcane spell, this creature gets +1/+1 until end of turn."
Scaled Hulk71%
$0.19↓#30445↓0.27↑21.6 years↑
"Whenever you cast a Spirit or Arcane spell, this creature gets +2/+2 until end of turn."