As long as you are not cracking too many Clues and leave yourself two or more, you have a great colored mana source from this Doctor Who card
The import side is the part that used to feel out of reach, and it no longer has to be
This is an interesting way to incentivize attacking players other than you and can be quite interesting when equipped to a card like Phyrexian Crusader
For reference, before the tax was added to the Companion mechanic, as long as you upheld the deckbuilding restriction that the Companion requested, you could add your Companion from the Companion zone (your sideboard) to your hand at no cost essentially allowing you to begin the game with a guaranteed extra card in hand
Valiant Changeling Valiant Changeling makes this list based on the synergies with other changelings
If you want to control the game by tactically applying auras and forcing your opponents into attacking one another, go with SIlverquill Influence