Herculean (?.)

• Antaean
• Atlantean
• Briarean
• Brobdingnagian
• Cyclopean
• Gargantuan
• Homeric
• abstruse
• abysmal
• arduous
• astronomic
• backbreaking
• brutal
• burdensome
• colossal
• complex
• critical
• crushing
• delicate
• demanding
• difficile
• difficult
• effortful
• elephantine
• enormous
• epic
• exacting
• forced
• formidable
• gargantuan
• giant
• giantlike
• gigantic
• grueling
• hairy
• hard
• hard-earned
• hard-fought
• heavy
• hefty
• heroic
• huge
• immense
• infinite
• intricate
• jawbreaking
• jumbo
• killing
• knotted
• knotty
• labored
• laborious
• mammoth
• mean
• mighty
• monster
• monstrous
• monumental
• mountainous
• no picnic
• not easy
• onerous
• operose
• oppressive
• painful
• prodigious
• profound
• punishing
• rigorous
• rough
• rugged
• set with thorns
• severe
• spiny
• steep
• strained
• strenuous
• stupendous
• thorny
• ticklish
• titanic
• toilsome
• tough
• towering
• tremendous
• tricky
• troublesome
• uphill
• vast
• wearisome
• wicked