P5 the Old Stag: standing stones and altar, three-phase boss with charges, stun window, spirit wolves and stomps; antler pickaxe and trophy; group scaling and credit for every fighter; online 3-player test (protocol 12)

docs/PROGRESSION_DESIGN.md

@@ -1,7 +1,6 @@
 # Progression and challenges design
 
-Status: **P1 (iron), P2 (stone), P3 (adversaries) and P4 (hazards)
-built**; P5 is a proposal.
+Status: **P1-P5 built** (iron, stone, adversaries, hazards, the Old Stag).
 
 *As built in P1:*
 - Iron nuggets (70, in the scree under the rim), clay (60, on the lake
@@ -123,6 +122,35 @@ built**; P5 is a proposal.
   It burns 40 s (you can warm yourself by it), falls, and leaves 2 charcoal.
 - Network protocol 11.
 
+*As built in P5 (the Old Stag):*
+- The standing stones: 7 tall stones in a ring at the foot of the rim with
+  an altar in the middle (from the seed; 60 m+ from the spawn and den, 50 m+
+  from the barrow, 42 m+ from the bear's home). E on the altar sets barrow
+  key pieces in its three hollows; with all three in, at night, it calls
+  the Old Stag.
+- The Old Stag: 900 health, 3.8 m at the shoulder. It circles, lowers its
+  antlers (1.2 s warning), and charges in a straight line through where
+  you were: 30 if it catches you, nothing if you step aside. Then it's
+  stunned for 2.5 s, when hits do half as much again. Below 2/3 it calls 3
+  spirit wolves; below 1/3 2 more, quicker warnings (0.8 s), a 1.5 s stun,
+  and a stamp (15 to anyone within 5.5 m, every 4 s). No fear of fire.
+- It goes back into the mist at dawn, or 5 s after everyone's left the
+  stones or died: the key pieces stay in the altar for another night.
+- Beaten: its antler and a trophy (a placeable stand) where it fell, the
+  key pieces used up, and the world remembers (day and, on a server, who;
+  everyone's told). Three new key pieces call it again.
+- In a group (on a server): anyone can set key pieces in the altar. It has
+  60% more health for each extra living player within 45 m when it's
+  called (900 alone, 1980 for three), and calls one more wolf each time for
+  each extra player (up to 4 more). It remembers everyone whose blow,
+  arrow or spear hit it; when it falls, all of them are named ("Beaten by
+  Alice, Bob and Cara on day 2") and saved. The antler and trophy go to
+  whoever picks them up first (tests/test_net_boss.gd: three players).
+- Antler pickaxe (forge: the antler, an iron bar, 2 wood): tier 3, 3.0 a hit
+  (iron 2.0), 250 uses (iron 200), 4 stamina a swing (iron 6).
+- Network protocol 12; creature health now goes over the wire in tenths
+  (up to 6553), so the stag's 900 fits.
+
 Today the island runs out of goals after a few days: once you have stone
 tools, a hut, a bow and a fire, the only threats are wolves at night, the
 cold and your diet. This plan adds a **second tier of materials** (iron and