Originally Posted by
Parcher
The one DR does come in against Extraction. It is there, however, mainly for Land-based decks that we can't normally interact with. Rider serves the same purpose as Terastodon as far as removing troublesome permanents. Rider has some advantages though. It can remove creatures, which is barely relevant. But against Lands and Post there are two major upgrades. Oftenyou can go off, and they already have the Chasm, Tabernacle, etc. in hand. The Don really wont get full value there, where Rider laughs at both Tabernacle and Chasm even if already in play. Also, Rider exiles said lands so they can't Loam them back. The deck doesn't need any help adding more DR targets for other matchups.
The extra lands are to enable Decay, and/or against Tempo decks. The Petals come against any Combo, and decks without countermagic, or a turn one/zero hate sweeper. With any discard spell, any draw spell, a land and a dredger, and/or drawing any of these missing pieces off a T1 cantrip, Petal effectively is at least a time walk.