War Falcon 
Creature — Bird
Flying
This creature can't attack unless you control a Knight or a Soldier.
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Cards that do something similar 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.
Lovestruck Beast // Heart's Desire 88%
$0.23#12443
"This creature can't attack unless you control a 1/1 creature."
Goblin Cohort 87%
$0.24#24308
"This creature can't attack unless you've cast a creature spell this turn."
Mogg Conscripts 87%
#27105
"This creature can't attack unless you've cast a creature spell this turn."
Bloodcrazed Goblin 87%
$0.18#25197
"This creature can't attack unless an opponent has been dealt damage this turn."
Silburlind Snapper 86%
$0.04#26997
"This creature can't attack unless you've cast a noncreature spell this turn."
Mogg Toady 86%
$0.11#30572
"This creature can't attack unless you control more creatures than defending player."
Goblin Goon 86%
$0.35#20282
"This creature can't attack unless you control more creatures than defending player."
Harbor Serpent 86%
$0.14#20206
"This creature can't attack unless there are five or more Islands on the battlefield."
Orcish Conscripts 86%
#30294
"This creature can't attack unless at least two other creatures attack."
Lambholt Pacifist // Lambholt Butcher 86%
$0.21#23485
"This creature can't attack unless you control a creature with power 4 or greater."
Warden of the Chained 86%
$0.10#27889
"This creature can't attack unless you control another creature with power 4 or greater."
Crown-Hunter Hireling 85%
$0.18#24193
"This creature can't attack unless defending player is the monarch."
Lurking Green Dragon 85%
$0.21#22222
"This creature can't attack unless defending player controls a creature with flying."
Vantress Gargoyle 84%
$0.32#11501
"This creature can't attack unless defending player has seven or more cards in their graveyard."
Scarred Puma 84%
$0.08#31128
"This creature can't attack unless a black or green creature also attacks."
Orgg 83%
$0.28#31281
"This creature can't attack if defending player controls an untapped creature with power 3 or greater."
Goblin Mutant 83%
#30681
"This creature can't attack if defending player controls an untapped creature with power 3 or greater."