A Rare Glyph starts at radius 3, grows to radius 4 at Glyph level 15, and radius 5 at level 50; at level 51 it upgrades from Rare to Legendary and gains an entirely new Legendary Bonus effect, which then continues scaling in strength all the way to level 150.
Radius controls how many nearby Paragon board nodes the Glyph's bonus affects, so each radius breakpoint is a step-change in how much of the board benefits, not a smooth curve - identical in spirit to Attack Speed's frame breakpoints but for Paragon investment instead of combat stats.
Both the radius increases and the Rare-to-Legendary upgrade are hard level thresholds built into the Glyph XP curve, not gradual scaling; a Glyph at level 49 provides meaningfully less board coverage and no Legendary Bonus at all compared to the same Glyph at level 51.
Radius 3 (base) -> Radius 4 (level 15) -> Radius 5 (level 50) -> Legendary upgrade + new Legendary Bonus effect (level 51) -> Legendary Bonus continues scaling to level 150 (its own max).
Feed post-dungeon Glyph XP into a small core rotation of Glyphs until each clears level 15, then 50, then 51, before spreading XP thin across many Glyphs - a level-14 Glyph and a level-49 Glyph are both leaving a breakpoint on the table.
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