Cheapest priced copy (The Lost Caverns of Ixalan Commander): $4.99 at Card Kingdom, near mint, their price list as of .
Evolution Sage 
Creature — Elf Druid · 3/2 · Uncommon · War of the Spark · #159
Landfall — Whenever a land you control enters, proliferate. (Choose any number of permanents and/or players, then give each another counter of each kind already there.)
Legal inCommanderPioneerModernLegacyVintage
Not legal inBrawlStandardPauper
8 printings · $4.99 to $34.99 at Card Kingdom
| Set | Number | Rarity | Card Kingdom | Foil |
|---|---|---|---|---|
| Lorwyn Eclipsed Commander | 105 | Uncommon | $5.49 | — |
| The Lost Caverns of Ixalan Commander | 240 | Uncommon | $4.99 | — |
| New Capenna Commander | 287 | Uncommon | $5.49Out of stock | — |
| Phyrexia: All Will Be One Commander | 108 | Uncommon | $5.99 | — |
| The List | WAR-159 | Uncommon | $5.49 | — |
| Secret Lair Drop | 765 | Rare | — | $34.99 |
| War of the Spark | 159 | Uncommon | $5.99 | $16.99 |
| Zendikar Rising Commander | 65 | Uncommon | $5.49 | — |
9 rulings from Wizards of the Coast
- 4 February 2023If a permanent ever has both +1/+1 counters and -1/-1 counters on it at the same time, they're removed in pairs as a state-based action so that the permanent has only one of those kinds of counters on it.
- 4 February 2023Players can respond to a spell or ability whose effect includes proliferating. Once that spell or ability starts to resolve, however, and its controller chooses which permanents and players will get new counters, it's too late for anyone to respond.
- 4 February 2023An ability that triggers "Whenever you proliferate" triggers even if you chose no permanents or players while doing so.
- 4 February 2023You don't have to choose every permanent or player that has a counter, only the ones you want to add another counter to. Since "any number" includes zero, you don't have to choose any permanents at all, and you don't have to choose any players at all.
- 4 February 2023To proliferate, you can choose any permanent that has a counter, including ones controlled by opponents. You can choose any player who has a counter, including opponents. You can't choose cards in any zone other than the battlefield, even if they have counters on them.
- 4 February 2023If a player or permanent has more than one kind of counter on it, and you choose for it to get additional counters, it must get one of each kind of counter it already has. You can't have it get just one kind of counter it already has and not the others.
- 8 November 2024A landfall ability doesn't trigger if a permanent already on the battlefield becomes a land.
- 8 November 2024Whenever a land you control enters, each landfall ability of the permanents you control will trigger. You can put them on the stack in any order. The last ability you put on the stack will be the first one to resolve (As a result, you can have those abilities resolve in the order of your choosing.).
- 8 November 2024A landfall ability triggers whenever a land you control enters for any reason. It triggers whenever you play a land, as well as whenever a spell or ability puts a land onto the battlefield under your control.