The first scenario, The Gathering , in the core is very much of a tutorial, designed to give you a straightforward situation to get yourself familiar with the mechanics of the game
Immediately after this effect resolves, Link Summon 1 Fiend monster using that target and 1 "Unchained" monster you control as material
Corrupted Corrupted is a new ability word that highlights abilities that care whether an opponent has three or more poison counters
Maybe you could use OR (like this, with capital letters), but I think my suggestion avoids any problem you could have, and final clause was changed so you can only use 1 effect per turn even if they're separated
Trainer Cards are split into two types primarily: Items, which you can use as many of as youd like each round, and Supporters, which you can only use once per round