Generator Servant
Creature — Elemental
, Sacrifice this creature: Add 
. If that mana is spent on a creature spell, it gains haste until end of turn. (That creature can attack and as soon as it comes under your control.)
Infinite potential given finite form.
Mathias Kollros
Ultimate Masters (UMA)
• #133Rulings
An instant or sorcery spell is not a creature spell, even if that spell creates creature tokens.
(wotc • 2018-12-07)
If the mana is spent on two different creature spells, each of those spells (and resulting creatures) will gain haste until end of turn.
(wotc • 2018-12-07)
If the mana is spent on a noncreature spell that becomes a creature later in the turn, that creature won't have haste.
(wotc • 2018-12-07)
If a creature spell has generic mana only in its alternative or additional cost, the creature will still gain haste.
(wotc • 2018-12-07)
Rulings
An instant or sorcery spell is not a creature spell, even if that spell creates creature tokens.
(wotc • 2018-12-07)
If the mana is spent on two different creature spells, each of those spells (and resulting creatures) will gain haste until end of turn.
(wotc • 2018-12-07)
If the mana is spent on a noncreature spell that becomes a creature later in the turn, that creature won't have haste.
(wotc • 2018-12-07)
If a creature spell has generic mana only in its alternative or additional cost, the creature will still gain haste.
(wotc • 2018-12-07)