Boulderback

The 8.2K HP boss at wave 30

Boulderback is BOSS - WAVE 30 on the red header: HP 8.2K, DMG 70, SPD 2.6, $1,200. Its SPD pill is the lowest on the whole index; no other card prints 2.6.

The HP pill is the largest before Gravemaw's 13K at wave 50. DMG 70 is below the previous red boss, Titanhorn at 90, so this card adds HP and gives up damage.

Its two neighbours in the red set are faster: Titanhorn prints SPD 3.5 and Gravemaw 4.2. Boulderback trades that speed for 8.2K HP at wave 30, so it is the slow wall rather than the damage card.

Red bosses around wave 30

The red line is not a straight damage upgrade. Titanhorn prints DMG 90 at $900, Boulderback drops to 70 at $1,200, and Gravemaw jumps back to 130 at $1,600. Boulderback is the only one of the three that loses DMG while gaining price.

HP per dollar is 6.8 here, close to Titanhorn's 6.7 and below Gravemaw's 8.1. Damage per dollar is 0.06, the weakest of the first three red cards.

Wave 30: hold the line or skip?

The next red card after wave 30 is Gravemaw at 50, twenty waves away. Gravemaw prints 1.6 times the HP, 1.86 times the DMG and 1.33 times the price of Boulderback, so saving for it is an upgrade on both attack columns.

If you can hold $1,200 at wave 30, Boulderback doubles the biggest HP pill you can own at that point. If your cash is still in the tens, the card is a later purchase; the header only prints the unlock wave, not a requirement for the wave 30 fight.

One red row, no juvenile

There is no Juvenile Boulderback and no variant label on the card. The boss set runs Titanhorn 10, Boulderback 30, Gravemaw 50, Wrecker 70 and Skyreach 90, then every 20 waves to Grovebreaker 250. The gold mini-bosses at 20 and 40 fill the gaps.

After Boulderback, Gravemaw is the next red row and the next HP step. The card has no level field, so the upgrade path is a different card rather than a level on this one.