Intruder Alarm

Creatures don't untap during their controllers' untap steps.
Whenever a creature enters, untap all creatures.

Devoted Druid

{T}: Add {G}.
Put a -1/-1 counter on this creature: Untap this creature.

Whenever this creature becomes tapped, you may create a 1/1 blue Merfolk Wizard creature token.

Tap an untapped Merfolk you control: Target player mills a card.

({T}: Add {G} or {W}.)
As this land enters, you may pay 2 life. If you don't, it enters tapped.

Whenever another creature enters, untap this creature.

This land enters tapped unless you control a Forest or a Plains.
{T}: Add {G} or {W}.

Other Elves you control get +1/+1.
{G}, {T}: Create a 1/1 green Elf Warrior creature token.

This land enters tapped unless you control two or fewer other lands.
{T}: Add {W} or {U}.

Enchant creature
Enchanted creature has "{T}: Create a 1/1 green Elf Warrior creature token."

({T}: Add {G} or {U}.)
As this land enters, you may pay 2 life. If you don't, it enters tapped.

Enchant creature
Enchanted creature gets +1/+1 for each creature you control.
Cycling {G/W} ({G/W}, Discard this card: Draw a card.)

Search your library for an enchantment card, reveal it, put it into your hand, then shuffle.

This land enters tapped unless you control a Plains or an Island.
{T}: Add {W} or {U}.