Khalni Heart Expedition is the first card I'd consider adding. When comboing off it will give you 4 more landfall triggers (crack, fetch 2 basics, second sunrise, get quest counters off ghost quarters and such, crack again). Might need to increase basic land count.
Explore helps you dig deeper when you need to combo and gives another landfall.
Harrow will recycle more lands with second sunrise and give you two more landfall triggers.
Edge of Autumn can be cycled if you don't have gargodon or can be cast to fetch out another land.
Dreamscape Artist if you feel like expanding into blue. Although 2U might be a bit expensive. Harrow is on colour and does the same.
Shard Volley another way to sac lands if you don't have a gargadon. Becomes a free 3 damage when second sunrise will fetch the land back untapped.
On the topic of Flagstones, they also get mistveil plains and Godless Shrine, and the thinning/shuffle can be very tech.
Also works well with ghost quarter in the matches where quarter isn't relevant. EOT turn on Emeria, when they thought they had at least 2 turns is always fun.
I've been absolutely loving the switch to include suppression field in my hybrid martyr/sisters deck. It has some counter synergies with mistveil and martyr but you can often play around the martyr at least.
Manabases are so greedy right now. Rightfully so with no wasteland or price of progress. Although it won't kill fetchlands and manlands like needle, time walk whenever they crack a fetch sounds good to me.
Living end, pod, kiki-twin, aether vial, tron, planeswalkers... Nope.
Not to mention that many sideboards are running ancient grudge without anything to deal with enchantments (there aren't many to deal with) which makes it completely unremovable in most games.
Weathered Wayfarer over Bob comes out a turn earlier at the expense of pay W to "draw". It would also allow you to run more expensive cards without having to worry about flipping them to bob.
Liliana and discard is hard to replace. So you would have to go in a different direction. Knight and Loam have a bit of anti-synergy but 6 damage from assault and +3/+3 on knight can certainly throw off opponent's combat math.
Gaddock only stops our worm harvest but can screw over a number of other decks. Without the discard, combo matches become more difficult but canonist can solve that.
Less combo:
Although it looks like a fun deck when it does go off, I think straight Boros will be far more consistent.
EDH player? Mana breach isn't modern legal and strip mine isn't even legal in vintage...
Bouncing lands just slow rolls the landfall triggers. With Second sunrise you're looking to combo off.
Crab is off colour and unless you plan on decking them or using your own graveyard, the landfall will be insignificant.
Also works well with ghost quarter in the matches where quarter isn't relevant. EOT turn on Emeria, when they thought they had at least 2 turns is always fun.
Manabases are so greedy right now. Rightfully so with no wasteland or price of progress. Although it won't kill fetchlands and manlands like needle, time walk whenever they crack a fetch sounds good to me.
Living end, pod, kiki-twin, aether vial, tron, planeswalkers... Nope.
Not to mention that many sideboards are running ancient grudge without anything to deal with enchantments (there aren't many to deal with) which makes it completely unremovable in most games.
1 Knight of the Reliquary
1 Kitchen Finks
1 Path to Exile
1 Horizon Canopy
1 Qasali Pridemage
1 Gaddock Teeg
1 Ethersworn Canonist
Weathered Wayfarer over Bob comes out a turn earlier at the expense of pay W to "draw". It would also allow you to run more expensive cards without having to worry about flipping them to bob.
Liliana and discard is hard to replace. So you would have to go in a different direction. Knight and Loam have a bit of anti-synergy but 6 damage from assault and +3/+3 on knight can certainly throw off opponent's combat math.
Gaddock only stops our worm harvest but can screw over a number of other decks. Without the discard, combo matches become more difficult but canonist can solve that.