It refers to effects where the condition is whether "you control three or more artifacts." Now, please try translating the text of this card
Artifacts Now to my personal favorite section: I love artifacts, always have and always will, and it was these cards are what finally tipped my hand into buying into this set
Squee, Goblin Nabob Squee, Goblin Nabob is a really neat value card, as you can sacrifice or discard it to your hearts content
The main ones you're looking for are the 'Karn-struct' Construct tokens that get +1/+1 for each artifact you control
Void That creature gets -10/-10 until end of turn instead if a nonland permanent left the battlefield this turn or a spell was warped this turn
If the revealed card doesn't have a mana cost (because it's a land card, for example), its mana value is 0