Tolaria West / Turntimber, Serpentine Wood
/ Port of Karfell / Littjara Mirrorlake - Tolaria West can transmute into another Summoner's Pact for whichever creature fits your situation best. It can also become any land, a Chalice of the Void or Engineered Explosives if either is in the deck (or any other 0 CMC sideboard card). Turntimber, Serpentine Wood
is basically a land that doubles as a threat with any bounceland later in the game. It is very comparable to Tolaria West in functionality, except it cannot be fetched by Primeval Titan and is a much preferred untapped green source when needed (notable when trying to stretch your manabase a little too much). Port of Karfell is basically recursion of a titan that's uncounterable in most situations and Littjara Mirrorlake lets you clone a copy, great for cheating in another attacker with 2+ amulets.
Valakut, the Molten Pinnacle - this is actually a win-con with enough land drops and Dryad of the Ilysian Grove. Due to the Bouncelands being able to bounce themselves, you are generally able to utilize all your extra land drops on each turn, so this damage can add up really quickly. It can be used to clear the board or to do direct damage.
Vesuva - this is essentially a mandatory include because of all the great plays it enables. Vesuva is probably the best land in the deck, as it can be pretty much anything. In addition to copying anything (opponent's lands included), you can play it untapped copying nothing with Dryad of the Ilysian Grove out to produce mana, an often overlooked line of play.
Boseiju, Who Endures - One of the best utility lands for the deck, since we can easily bounce it back to hand, making it fetchable removal for artifacts, enchantments, and even troublesome lands (essentially a broader version of Ghost Quarter if you don't plan to use it on yourself). It does technically ramp your opponent in most cases, but that's a fair tradeoff for eliminating a more troublesome permanent.
Cavern of Souls - good for control matches, and it can also be useful for colored mana when trying to hard cast more color intensive creatures like Sigarda, Host of Herons. Since we have a lot of bouncelands in here, we can change the creature type named almost as often as wanted, so this is almost like an Ancient Ziggurat that can tap for colorless when not casting creature spells.
Slayers' Stronghold / Hanweir Battlements
- some of the best utility lands for this deck. It allows your titans to come out with haste, you can't really ask for more. Slayers' Stronghold is the better of the two, since it gives haste/vigilance and +2/0, which can be important with enabling Mosswort Bridge triggers. Having both as an option gives you a lot of flexibility in your plays, and makes us less susceptible to things like Surgical Extraction or drawing into our only haste enabling land before playing the titan. Be careful not to overcommit to non-green lands though, as you need green lands for the deck to function early. I generally suggest choosing at most 2 between these and Sunhome, Fortress of the Legion as you don't want colorless sources as much.
Sunhome, Fortress of the Legion / Sejiri Steppe / Mosswort Bridge - Sunhome, Fortress of the Legion is great to block something with deathtouch (take that Wurmcoil Engine - I live and you don't even gain life), or just double your damage. However, Sejiri Steppe accomplishes one of the main goals of this utility slot, which is to help your Primeval Titan live after attacking (against most decks), but it requires no investment of to activate. This slot is unneeded in some matches, so it can easily be sided out when it's not that relevant. Sejiri Steppe + Mosswort Bridge cover the defensive and offensive purposes of Sunhome, Fortress of the Legion in almost every situation, without the need of as much mana investment, even allowing more aggresive plays sometimes, all while being colored mana sources instead of colorless. Mosswort Bridge is the most powerful digging tool and virtual advantage this deck has to offer. Cast off anything for 1 green? Yes please! Need to find some removal because they are just stalling with something stupid and annoying? Keep copying/bouncing this until you find what you are looking for. If you are running Mosswort Bridge, it is basically required to run Slayers' Stronghold + Boros Garrison alongside it, allowing you to get to 10+ power far more consistently. Because of those mandatory inclusions, Sunhome, Fortress of the Legion is a basically equivalent option as well, being in the same colors. Also worth mentioning is that you can use the hideaway of Mosswort Bridge to exile cards you don't want to draw, if you don't plan on activating it prior to bouncing it back to your hand. After a shuffling effect, this deck-thinning helps increase your odds of hitting cards you do want by a few percentage points.
Castle Garenbrig - this is decent as potential ramp if you run enough fetches + Forest Subtypes that it can consistently come out untapped. Not really worth forcing into the deck, but it can be viewed as +2 for mana calculations in a lot of scenarios, so definitely a solid include if there's enough space and support for it.
Urza's Saga / The Mycosynth Gardens - These are super powerful in game 1, but they are also super vulnerable to removal/hate (you basically concede against an early Blood Moon, Magus of the Moon, or Force of Vigor). However, one thing they both do well is allow for a double amulet more often (making them a solid turn 1/2 land). One additional upside the Saga does have going for it is the negatives aren't really preyed upon until games 2/3 of the match making it a powerful game 1 tool, which is why most decks want 4 copies, then side them out as needed. The Mycosynth Gardens needs a first Amulet of Vigor to copy, but it can have us go +1 the same turn, instead of needing to wait. It is a little less vulnerable to hate than its counterpart, since it isn't a Saga or Enchantment, but a little less powerful overall. When comparing the two, Urza's Saga is an investment of 2 turns for an Amulet of Vigor, while The Mycosynth Gardens is an investment of 2 mana, which also requires a first copy for us to copy. While it is pretty clear which of these effects is more powerful, both cards enable us to have an explosive turn 3 more consistently. These are also both colorless lands, which is something you need to be careful of running too many copies of, especially if you have a lot of early plays that want colored mana.
Forest / Snow-Covered Forest - basic lands are needed, enough said. It stops Path to Exile-type effects from being as devastating, and gives hope against Blood Moon. I typically like to use white bordered basics to make fetching easier (you can fan out your deck instead of going card by card) if going with fetchlands, just a little trick I like to use to help speed up games.
Selesnya Sanctuary / Golgari Rot Farm / Simic Growth Chamber / Gruul Turf - green bouncelands, the main thing this deck revolves around. It is a good idea to keep one of these in hand at all times (or a Vesuva to copy one) to make the most of your multiple land drop potential. The only time I play my last one in hand is if it means I can hard cast a bomb that I feel will get through when I untap next turn. Otherwise it is best to keep one in hand with the potential of drawing extra land cards, allowing you to "go off" in a lot of cases (considering you have either an amulet in play, or dryad/azusa in hand, and are just waiting on the other piece).
Crumbling Vestige - You can produce mana without an Amulet of Vigor out off a Primeval Titan fetch. You can also go +1 land with Crumbling Vestige + Slayers' Stronghold instead of Boros Garrison + Slayers' Stronghold when you have Dryad of the Ilysian Grove out, and sometimes that one land can be the difference that enables more burn damage with Valakut, the Molten Pinnacle.
Verdant Catacombs / Overgrown Tomb / Zagoth Triome - Fetches / Shocks / Triomes just enable better mana fixing, landfall triggers, and deckthinning. The triomes can also become card draw when bounced if needed. You should generally pick 5 color lands or fetches, it's a little hard to support both. I generally go with fetches alongside at least one shock, because you still have all the untapped potential, but can choose for them to be tapped sources as well, to make the most of multiple Amulet of Vigor lines.
Aether Hub / Gemstone Mine / Tendo Ice Bridge / City of Brass / Mana Confluence / Vivid Grove / Nurturing Peatland / Yavimaya, Cradle of Growth / Reflecting Pool / Twilight Mire - Gemstone Mine is probably the best of the rest, since you can use it twice then bounce it to reset its counters. Aether Hub is a strictly better version of Tendo Ice Bridge and is next in line, since you can bounce it and replay it without using the to stack multiples for later. City of Brass deals 1 damage whenever tapped and Mana Confluence allows you to pay 1 life for any colored mana, which are very important distinctions, and here's why: City of Brass will deal damage to you no matter if you have a replacement effect on it or not, so things like Yavimaya, Cradle of Growth or Dryad of the Ilysian Grove don't help you. However, since it is damage, and not loss of life, it doesn't conflict with Elderscale Wurm or Worship. Mana Confluence is the complete opposite, so if you use it's mana ability with Elderscale Wurm out and go under 7 life, his ability doesn't prevent it, and you are basically vulnerable again. Vivid Grove comes into play tapped, essentially making it the worst of the bunch as it can sometimes takes away strong turn 1 potential. The draw-land cycle of cards like Nurturing Peatland is one land that actually isn't terrible to draw when mana-flooded. Yavimaya, Cradle of Growth gives all lands the ability to tap for which allows the deck to stretch it's manabase a little thinner. The filter cycle like Twilight Mire helps manafix if you have a lot of non-green double cost cards. Reflecting Pool is basically a psuedo-5-color land that makes cards with multiple of the same color cost a lot easier to cast. It gets exponentially better with more multicolored lands, and is quite nice in greedy manabases like this one.
Lair of the Hydra / Oran-Rief, the Vastwood / Turntimber Grove - Lair of the Hydra is a green land that is untapped when you need it early, so basically another Forest. However, this is a manland, which can let you pump your total power on a titan fetch, or become a threat on its own. Oran-Rief, the Vastwood is great with the prevalence of Unholy Heat in the meta, being able to protect a Primeval Titan by just leaving it untapped, or just pumping creatures, sometimes enough for a Mosswort Bridge activation. Similarly, Turntimber Grove works pretty much the same, but it is better on the titan fetch (being able to pump and tap for ), but is not reusable every turn without other support.
Lotus Field / Flagstones of Trokair - Typically these two lands are a package deal, as they are a nice fetch-combo when you need lots of mana. These are capable of producing 5 mana per Amulet of Vigor and still netting you +2 lands for your Valakut, the Molten Pinnacle triggers when fetched. Lotus Field is also capable of pumping our Elvish Reclaimer on its own (can be used after blocking). Flagstones of Trokair being a non-green source, and Lotus Field decimating your land count on their own are substantial downsides to consider, so you need enough synergy to justify inclusion of these. You'll often see these alongside Elvish Reclaimer due to the great synergy.
Crystal Grotto / Temple of Plenty / halimar depths(wwk) - scry lands. If there's not a whole lot of early plays that need a turn 1 untapped land in your 75, the scry outweighs the slower land in most cases. Crystal Grotto is Zhalfirin Void 2.0, which can let you mana-fix as well, now giving you a relevant untapped version of the temples. Halimar Depthsis similar in functionality.
Ghost Quarter / Field of Ruin - land destruction that can double as another copy of a Forest if facing hate like Blood Moon. It's worth mentioning - don't hesitate to blow up your own lands with Ghost Quarter for landfall or The Gitrog Monster triggers - this has saved me on numerous occasions. It is actually a 3 mana land when fetched by Primeval Titan with Lotus Cobra or Tireless Provisioner out (two landfalls + green). It also allows you to draw 2 cards with The Gitrog Monster (one on the sacrifice cost, then one on the land destruction). In most cases, Boseiju, Who Endures is superior due to the added flexibility, but these are still solid options worth mentioning, especially if you have a way to recur lands from your graveyard. Ghost Quarter is especially good against something that lets you play lands from the graveyard, completely decimating your opponent's access to splash colors.
Khalni Garden / Radiant Fountain / Kabira Crossroads / Blossoming Sands cycle - chump blocker or lifegain slot. Sometimes that is enough to turn the tide of battle, so it isn't to be under-estimated as a utility option. I generally go with Khalni Garden / Kabira Crossroads if I have enough space (can potentially filter the with Wooded Bastion).
Blast Zone - This is more of a utility land to deal with the decks that pump out tons of low cost creatures/board presence. This is basically an Engineered Explosives attached to a land. It's biggest drawback is that it can't hit 0 cost permanents, since it enters with 1 counter on it already. You can also use it to blow up some big hard to remove threat with hexproof/shroud if you have enough mana.
Arena / Quicksand / Eiganjo, Seat of the Empire - targeted removal with their own respective pros and cons. Notably, Arena + Sejiri Steppe have decent synergy as a Primeval Titan fetch package. However, Arena not producing its own mana is the main thing holding it back, so you should consider it as more of a fetchable creature removal than a land if trying to fit it in. Quicksand is probably my favorite of the bunch.