Slithering Shade 
Creature — Shade
Defender (This creature can't attack.)
{B}: This creature gets +1/+1 until end of turn.
Hellbent — This creature can attack as though it didn't have defender as long as you have no cards in hand.
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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.
Geist of the Lonely Vigil 100%
$0.12#28971
"This creature can attack as though it didn't have defender as long as there are four or more card types among cards in your graveyard."
Ogre Jailbreaker 100%
$0.03#27254
"This creature can attack as though it didn't have defender as long as you control a Gate."
+1 more matching line
Chaos Lord 90%
$0.52#26305
"This creature can attack as though it had haste unless it entered this turn."
Bloodcrazed Goblin 89%
$0.18#25197
"This creature can't attack unless an opponent has been dealt damage this turn."
Goblin Cohort 88%
$0.24#24308
"This creature can't attack unless you've cast a creature spell this turn."
Mogg Conscripts 88%
#27105
"This creature can't attack unless you've cast a creature spell this turn."
Scarred Puma 85%
$0.08#31128
"This creature can't attack unless a black or green creature also attacks."
Silburlind Snapper 84%
$0.04#26997
"This creature can't attack unless you've cast a noncreature spell this turn."
Mogg Toady 84%
$0.11#30572
"This creature can't attack unless you control more creatures than defending player."
Goblin Goon 84%
$0.35#20282
"This creature can't attack unless you control more creatures than defending player."
Weathered Sentinels 83%
$0.86#2869
"This creature can attack players who attacked you during their last turn as though it didn't have defender."