Keyword: Graft

Graft 5 (This creature enters the battlefield with five +1/+1 counters on it. Whenever another creature enters the battlefield, you may move a +1/+1 counter from this creature onto it.)
Vigean Hydropon can’t attack or block.

Graft 3 (This creature enters the battlefield with three +1/+1 counters on it. Whenever another creature enters the battlefield, you may move a +1/+1 counter from this creature onto it.)
: Target creature with a +1/+1 counter on it gains shroud until end of turn. (It can’t be the target of spells or abilities.)

Graft 1 (This creature enters the battlefield with a +1/+1 counter on it. Whenever another creature enters the battlefield, you may move a +1/+1 counter from this creature onto it.)

Graft 6 (This creature enters the battlefield with six +1/+1 counters on it. Whenever another creature enters the battlefield, you may move a +1/+1 counter from this creature onto it.)
: Target creature with a +1/+1 counter on it gains trample until end of turn.

Graft 2 (This creature enters the battlefield with two +1/+1 counters on it. Whenever another creature enters the battlefield, you may move a +1/+1 counter from this creature onto it.)
: Regenerate target creature with a +1/+1 counter on it.