Diviner is an underpowered and boring alternative to Aiki. First, it's a single subroutine, which is a poor setup for playable ice. Of the 37 most commonly used ice, only 6 have one subroutine, and 5 of these (Ping, Tollbooth, Funhouse, Turnpike and Magnet) are mainly used for their ability and Vanilla is used as the cheapest gear-check to force runners to dig for a breaker. There's no scenario where Diviner is the best ice you could have. I don't even think there's a scenario where it's a good ice to have. It's too porous to reliably create short-term gains, and it's not efficient enough for long-term gains.
This card would be more interesting if it had 2 subroutines: 1) do one net damage, 2) reveal the top card of the stack and end the run if it has an odd cost. It is strange that Diviner as actually printed does not reveal any future knowledge. The only prediction we can make from Diviner is that you're not playing this card in standard, and nobody else is either.
(Thanks to Greasythumb for pointing out that Aiki has not rotated yet).
Not every card needs to be good, but Jinteki ice is dire right now, particularly in Startup (Engram Flush, Karuna, Saisentan, Lotus Field, Swordsman, Diviner). It's a rough time to be printing ice this bad.— superheronation
Aiki is still legal, and it's quite a different card. I agree that Diviner isn't a powerhouse, but not every card has to be. As a gearcheck codegate, I'd say Diviner's main competition is from Enigma, Whitespace and Thimblerig. All those have their advantages and disadvantages.— Greasythumb