Many decks that play Thoughtseize are also interested to add some copies of Inquisition, thats how strong this effect is
When this deck goes off, it can be nearly unstoppable
The name of the game for these commanders is to control the board, benefit from graveyard synergies, and slowly dwindle your opponents decks
Theyre too slow to move you from the early game to the mid game, cost a burdensome amount in the midgame when you want to play 2 moderately costed spells in a turn, and are just as unwelcome in the late game as their less expensive brethren when looking for a finisher or board wipe
Creatures you control can attack as though they didnt have defender, is the next line of text on Felothar, referring to an ability thats so central to the games core design that it was retroactively added to cards dating back to Magics first set, Alpha