⬤ Grey ring — LEAD: only Cannon, Tesla, Mortar, Plasma, Railgun, Sniper can hit. Slower.
⬡ Blue hex ring — SHIELD: absorbs N hits before taking damage. Number above shows hits left.
＋ Green pulse + cross — REGEN: heals over time if not under fire.
○ Gold layered ring — FORTIFIED: extra HP and slower.
▦ Dark green stripes — CAMO: only Laser, Sniper, Mortar, Plasma, Railgun, Nova, Sub can target.
Blue water lakes — only WATER towers (Boat, Sub) can be placed here.
Rocks / trees / crystals — block tower placement.
Dashed blue line — the path balloons follow.