Send ink. Drag from one of your cells to any cell your territory touches. Drag across several of your cells to send from all of them. Or tap a cell, then tap the target.
Wells feed you. A pool with a spinning ring is a well. Only cells joined to one of your wells grow. Cells that are cut off dry out and turn back to paper.
Flank. Hit a cell from two or more sides at once and every drop counts for more, up to ×1.75.
Pipes. In Pipe mode a drag sets a standing line: the cell keeps pumping ink along it. Tap a cell in Pipe mode to stop it. Hold Shift to pipe without switching.
Read the pools. Square pool: a bastion, defends double. Ringed pool: a basin, holds 80. Drops from two sides that meet on the way cancel out.