he Ire stones

[Hoid the Former Drifter he/him]

When Kelsier touches the stones of the Ire stronghold, he sees visions of a place with green plants. He also is suddenly able to understand their language. Does touching the stones create a Connection to Elantris?

[Honorless he/him]

They manifested the stones from the Physical Realm into the Cognitive Realm, 

(Stormlight Archive)

Spoiler

Like the spren do, as we saw in OB

Or Kelsier himself did with the flames

Investiture from the Dor was also being pumped into it, which was flowing through into the fortress and powering it, I suspect it was that which allowed the Connection.

[+Invocation]

Yeah, that's pretty much what happened there.