Colin Bakers Sixth Doctor card contains the ability Time Lords Prerogative, which allows players to copy any historic spells they cast once per turn, with the copy not being classed as legendary
Lands, Enchantments, Artifacts, even low mana value Planeswalkers are on the table when Tayam, Luminous Enigma starts digging
While a super aggressive sliver deck might not need this effect, it's invaluable in slightly slower strategies
Being as defensable as a Grey Orge there is relaitvely little chance of this eevr being too oppressive
Sure, your opponent cant do anything to you , but this creature still dies to a lot of removal spells while it gives you no value
Tajic is an incredibly good card, but it looks like some of the decks at the top of the expected week one metagame are built to deal with it efficiently