Is lost legacy a good counter to mardu vehicles and 4 color saheeli

[WayneD69]

If so which cards should be removed? If not a good option what else is good?

[ladof]

It probably could be for Saheeli, since you can just name Saheeli or the guardian, but Mardu Vehicles has a lot of threats and most of them are vehicles, so it wouldn't hit a lot of the things you'd want it to.

[Mnemosyne]

If so which cards should be removed? If not a good option what else is good?

If you look at Lost Legacy you'll see that you can only target non-artefact spells, which won't do much about a Mardu Vehicles like Ladof mentioned. Not just because of Heart of Kiran and Aethersphere Harvester are artefacts, but because of the reoccurring threats, Unlicensed Disintegration only needs an artefact as well as Toolcraft Exemplar and Inventor's Apprentice, so if you take away one, another one exists to take its place, and all you've done is delayed the player, temporarily.

I don't believe that Lost Legacy would be that useful for the Saheeli combo, you can use it only on turn 3, which is when Saheeli comes into play, assuming you've gone first. Then you have turn 4 to cast it to either remove Felidar Guardian or Saheeli, assuming that neither are on the field. The best defence against that deck would be to sideboard Authority of the Consuls into your main deck, because Felidar Guardian would come into play tapped, thus circumventing the combo.