The way challenging works is a ready (untapped) character exerts and chooses an opposing exerted character to challenge, and then both cards compare their strength (attack) and willpower (defense) values to each other (meaning the attacker automatically gets hit back by the defender)
The incidental burn for using artifacts is nice too, especially since it doesnt exclude mana abilities like these effects often do
When it enters the battlefield, it lets you draw cards equal to the number of permanents of CMC 3 or greater you control, which suggests a deck design that prioritizes permanents
That's understandable, this is the most valuable card in all MTG history and the highest sell yet
We all had a few Caterpies and Rattattas lying around from this trend, and if you managed to collect a coveted card like a holographic Charizard, you were the talk of the school playground and truly got lucky
These ultra-powerful cards represent other Planeswalkers (like you) who have come to help you win your battle