It's "just" a one-for-one, but if you either drew more Lands than your opponent or they just had a light draw, it could result in some un-fun non-games, especially in an era with less friendly mulligan rules

Advanced Search Sets Random Syntax A Tale for the Ages Ajani, Wise Counselor Alenni, Brood Recruiter Archfiend of Sorrows Armament Master Arms of Hadar Arvad the Cursed Bane of the Living Bane's Invoker Basri, Devoted Paladin Bastion Protector Bite of the Black Rose Biting Rain Black Panther, Most Dangerous Bloodstoke Howler Bloodsworn Steward Bold Defense Cemetery Reaper Choking Miasma Chronicle of Victory Claws Out Colossal Heroics Common Cause Cry of the Carnarium Crystallized Serah Dauntless Onslaught Day of Destiny Death Frenzy Death Pit Offering Decimator of the Provinces Decree of Pain Defender of the Order Demon of Dark Schemes Dictate of Heliod Doctor Strange, Surgeon Drawn Together Drown in Sorrow Echoing Courage Echoing Decay Elesh Norn, Grand Cenobite Ellywick Tumblestrum Elspeth's Talent Elspeth, Sun's Champion Encampment Keeper End-Raze Forerunners Engineered Might Eyeblight Massacre Familiar Beeble Mascot Fancy Footwork Fear My Authority Fecund Greenshell Flaying Tendrils Flower // Flourish Flower // Flourish For the Emperor

In order to figure out the result of a combat phase, you need to measure your Creatures' Power against your opponent's Creatures' Toughness (and vice versa)
OP-18 follows the standard One Piece TCG numbered set rarity structure all counts officially confirmed by Bandai
A Link Monster that used this card as material can also use 1 monster your opponent controls as material to Link Summon
With all three on the field, sac the Spider to activate the Altars mana ability