Saheeli, the Sun's Brilliance | Mana Echoes | Breaching Hippocamp

(and one other card)

Saheeli does not have summoning sickness.
({U} magic symbol) ({R} magic symbol) available, plus an additional ({U} magic symbol) ({R} magic symbol) if you control less than three creatures that share a creature type with
Breaching Hippocamp.

Activate
Saheeli by paying ({U} magic symbol) ({R} magic symbol) and tapping it, creating a token copy of
Breaching Hippocamp with haste.
When the token
Breaching Hippocamp enters the battlefield, it and
Mana Echoes trigger.
Resolve the
Breaching Hippocamp trigger, untapping
Saheeli.
Holding priority, if you control less than four creatures that share a creature type with
Breaching Hippocamp, repeat steps 1 through 3 one additional time.
Resolve all
Mana Echoes triggers, adding ({C} magic symbol) for each creature you control that shares a creature type with
Breaching Hippocamp for each trigger resolved this way.
Activate
Prismite twice by paying ({4} magic symbol) , adding ({U} magic symbol) ({R} magic symbol) .
Repeat.