Doubtless One

The block's tribal lords pumped from outside, but this one folds the count and the payoff into a single body: it is as large as the Cleric board it sits on (itself included), and every point of damage it lands refills your life total by the same amount. The two halves reinforce each other in a way most variable-sized creatures never manage. A typical / counts something and stops there; this one counts, then converts that count into lifegain that scales with its own growth. A wide Cleric board makes it enormous, an enormous attacker swings for a fortune of life, and a fat life total buys the time to keep the board wide. The Avatar tag in the type line marks it as the tribe's centerpiece, the card the whole Cleric package was built to climax into rather than just another anthem in the chain. The cost of that reach is fragility: strip away the other Clerics and it collapses to a 1/1 (it still counts itself), so a removal spell aimed at the supporting cast hits this card too. It asks you to commit a board, not bank on a single resolved threat. It is the rare lifegain finisher whose lifegain and finishing are the same act, and the Cleric count is at once its strength and the lever an opponent pulls to throttle it down.