Cards like Eldrazi Mimic

Halfdane83%

$35.97↑#28608↓0.0632.4 years↑

"At the beginning of your upkeep, this card's base power and toughness become equal to the power and toughness of target creature other than this card until the end of your next upkeep."

toughness-matters, shapechange, power-matters

Arni, Renowned Champion82%

$0.15↓#26706↓0.100.0 years↓

"Whenever another creature you control enters, this card gets +X/+0 until end of turn, where X is that creature's power."

creaturefall, scales-with-power, thingfall

Hulkling, Burgeoning Bruiser79%

$0.13↓#21862↓0.19↑0.3 years↓

"Whenever another creature you control enters, if it has greater power or toughness than this card, put a +1/+1 counter on this card."

toughness-matters, creaturefall, power-matters

Amplifire76%

$0.17↓#24938↓0.17↑7.7 years↓

"At the beginning of your upkeep, reveal cards from the top of your library until you reveal a creature card. Until your next turn, this creature's base power becomes twice that card's power and its base toughness becomes twice that card's toughness. Put the revealed cards on the bottom of your library in a random order."

toughness-matters, shapechange, scales-with-power

Unruly Krasis73%

$0.38↓#22363↓0.112.7 years↓

"Whenever this creature attacks, you may have the base power and toughness of another target creature you control become X/X until end of turn, where X is this creature's power."

shapechange, scales-with-power, power-matters

Hamletback Goliath72%

$0.20↓#92180.0619.0 years↑

"Whenever another creature enters, you may put X +1/+1 counters on this creature, where X is that creature's power."

creaturefall, scales-with-power, thingfall

Belligerent Yearling72%

$0.22↓#91750.002.9 years↓

"Whenever another Dinosaur you control enters, you may have this creature's base power become equal to that creature's power until end of turn."

shapechange, scales-with-power, power-matters

Galion, Elvenking's Butler72%

$0.16↓#20514↓0.100.2 years↓

"Whenever this card attacks, choose up to one other target creature you control. Its base power and toughness become equal to this card's power and toughness until end of turn."

shapechange, scales-with-power, toughness-matters

Shelinda, Yevon Acolyte72%

$0.22↓#5407↑0.121.4 years↓

"Whenever another creature you control enters, put a +1/+1 counter on that creature if its power is less than this card's power. Otherwise, put a +1/+1 counter on this card."

creaturefall, scales-with-power, thingfall

Evolving Adaptive71%

$0.19↓#17107↓0.063.7 years↓

"Whenever another creature you control enters, if that creature has greater power or toughness than this creature, put an oil counter on this creature."

toughness-matters, creaturefall, power-matters

Tanazir Quandrix70%

$0.32↓#8363↑0.86↑5.5 years↓

"Whenever this card attacks, you may have the base power and toughness of other creatures you control become equal to this card's power and toughness until end of turn."

shapechange, scales-with-power, toughness-matters

Sharp-Eyed Rookie70%

$0.17↓#17830↓0.152.7 years↓

"Whenever a creature you control enters, if its power is greater than this creature's power or its toughness is greater than this creature's toughness, put a +1/+1 counter on this creature and investigate."

toughness-matters, creaturefall, power-matters