Spider is a minion capable of moving only diagonally (until +++), and the only minion able to directly poison another unit.
Quick Stat: Spider Edit
|Tier 1||Tier 2||Tier 3||Tier 4|
Tier 2: Spider+ Edit
To Upgrade from Spider to Spider+, you need 5 Spider and 25 Dragon Coins.
Changes from Spider: Adds one extra move range in every diagonal direction
Tier 3: Spider++ Edit
To Upgrade from Spider+ to Spider++, you need 5 Spider+ and 100 Dragon Coins.
Changes from Spider+: Adds another diagonal move range
Tier 4: Spider+++ Edit
To Upgrade from Spider++ to Spider+++, you need 5 Spider++ and 500 Dragon Coins.
Changes from Spider++: Adds teleport in a knight pattern
Strategy: Spider Edit
Strength: Spider Edit
The lowly spider is easy to underestimate. For a 0 cost minion, Spiders offer an incredible amount of mobility and threat area. Individually they are very vulnerable, but a pair of spiders on opposite colors can walk across the battlefield together, keeping each other covered. Unlike most minions they can easily move backwards and side to side so they can (eventually) get wherever you want them to go, and few players will be willing to endanger a champion to take a couple of 0 cost minions.
Weakness: Spider Edit
A lone spider is practically defenseless and can be picked off easily, even by other minions. Also, while they offer decent area control, Poison is a terrible ability because it doesn't do anything instantly. Practically any attacking minion can march up and force a trade on their terms and still remain a threat for another turn or two. They may even be able to simply take a spider for free, or mow down multiple pieces in succession before the poison stops them.
Most players will be less willing to trade champions for a Spider, but Poison cannot stop pieces from threatening other pieces, making Poison less useful as a deterrent. Spiders are probably best used in sets of 2: a single spider is fairly useless, but too many spiders will leave you with an undefendable army.
The Spider has two incredibly debilitating weaknesses: the first is that its movements are color-locked and it cannot attack the color it is locked to. It does not lose this weakness until +++ rank. The other weakness is that it can only attack 1 space away, and attacks with poison, which means it will basically never survive attacking. The inherent problem with Spider is that isn’t actually powerful at any point in the game. In the early game, units are too closely packed together for the Spider to get close enough to them without dying. In the late game, there’s very little to stop any given piece from killing the Spider or just moving away. The only time when they’re really strong is when they’re forking two pieces AND you have them covered by another piece. This is pretty much never going to happen with any version of Spider except Spider+++, and even then it’s a rarity. All in all, it’s a piece that, in spite of its maneuverability, just can’t do what you need it to.