A reasonable approximation of the expected power of gold cards is that your 2nd colour of mana adds about a 1/3rd of a mana, the 3rd colour adds 2/3rds of a mana and the fourth is a whole extra mana
But, remember to include higher-cost, high-impact draw cards like Ambition's Cost , for when your mana pool deepens
Youre aiming to choose a creature to be exiled, otherwise the exiled card is wasted
Like a toddler in a sea of wrapping paper, Im baffled by all these glittering new things, but delighted by them regardless
Finally, because he can make many spells and abilities free, he can be the third card in numerous infinite combos, like Carrion Feeder and Gravecrawler, Necrotic Ooze with Asmodeus, the Archfiend in your graveyard, or even just K'rrik and Blood Celebrant, which essentially makes a free mana of any one color for each three life you pay
The card is a subset tutor (of sorts) from a very unpopular set, so I like it as a low-risk long-term hold