The Mindskinner

The Mindskinner can't be blocked.
If a source you control would deal damage to an opponent, prevent that damage and each opponent mills that many cards.

Sky Diamond

This artifact enters tapped.
{T}: Add {U}.

Frogify

Enchant creature
Enchanted creature loses all abilities and is a blue Frog creature with base power and toughness 1/1. (It loses all other card types and creature types.)

High Tide

Until end of turn, whenever a player taps an Island for mana, that player adds an additional {U}.