To be frank about it, I don't think Teferi's Response has any place in your 75.
It is a card with an extremely limited use in the deck, as it only possibly stops 2 cards in Legacy - Wasteland and Sinkhole. There aren't enough Pox decks to be significantly worried about Sinkhole, so that leaves only Wasteland as the sole reason to consider this card.
Now, currently, we have the following tools to combat Wasteland strategies:
- Crop Rotation (Respond to a Wasteland activation - Sacrifice the targeted land)
- Pithing Needle (MB or SB)
- Primeval Titan (A resolved PrimeTime renders Wasteland moot)
- Candelabra of Tawnos (Enables you to go off with less lands in play)
- Show and Tell (In a pinch, lets you cheat your win conditions into play)
- Bojuka Bog (To combat Life from the Loam shenanigans that have been popular lately)
As it stands, the above cards should be more than enough to get past Wasteland strategies - barring of course insane RUG hands, but then again, it wouldn't be called "insane" if it was easy to play against.
So personally, I would skip it and never look back.