Legendary Creature — Elf Scout
Whenever another creature enters, its controller may draw a card if its power is greater than each other creature's power.
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: Add X mana in any combination of colors, where X is the greatest power among creatures you control.
2/3

Green creature that taps for large mana scaling with creatures.

Devotion-based big green mana producer in same ramp role.

Other Selvala providing mana and card draw.

Elf that taps for mana scaling with creatures on board.

Card draw when creatures enter, similar engine.

Sac-based draw payoff for big creatures Selvala enables.

Draws cards when creatures enter, pairs with Selvala's draw.

Untaps lands/Selvala for explosive green mana ramp.
→ Infinite card draw, Infinite colored mana, Infinite draw triggers
→ Infinite colored mana, Infinite combat phases, Infinite untap of creatures you control
→ Infinite colored mana, Infinitely large creature until end of turn, Infinite untap of creatures you control
→ Infinite colored mana
→ Infinite LTB, Infinite ETB, Infinite colored mana
→ Near-infinite colored mana
Selvala's last ability is a mana ability. It doesn't use the stack and can't be responded to. If the greatest power among creatures you control is 0 or less at that time, no mana is added.
The new creature's power is compared to the power of each other creature on the battlefield as the first ability resolves. If another creature has the same or higher power than the new creature's power, no one may draw a card.
If the new creature isn't on the battlefield as the first ability resolves, use its power when it left the battlefield to determine whether its controller may draw a card. Note that effects that reduced its power before it left the battlefield will apply.