Fastest prowess you'll ever see (T1 win) (made by Grazjnok from TappedOut) (Casual)

Origins

This deck is inspired by a childhood memory of mine: seeing a guy whip out a Black Lotus, triplet of Moxes, Ball Lightning, Blood Lust, and Berserk for a turn 1 kill. Coming back to magic, 20+ years later, I decided I wanted to try and construct that very combo into a deck, modern legal. So I started with Ball Lightning, found myself a new Berserk in Assault Strobe and tried to figure out how to get the mana. Soon enough I figured out how to make a turn 3 kill. Then I worked out how to do it turn 2. Long story short, I've worked out my turn one kill combo. See below! Hope you enjoy it.
Feature cards

Monastery Swiftspear, Assault Strobe, Simian Spirit Guide.
Mechanics: turn one kill

Starting hand: 7 of the following, with room for an 8th card of your choice if you're not not starting play; Forest, Assault Strobe, Groundswell, Monastery Swiftspear, Mutagenic Growth, Simian Spirit Guide, Simian Spirit Guide.

Play Forest.
Exile Simian Spirit Guide to add R to your mana pool and play Monastery Swiftspear.
Exile other Simian Spirit Guide to play Assault Strobe, which gives it double strike and triggers the Monk's prowess ability, making it 2/3.
Tap Forest to play Groundswell, again triggering the monk's prowess ability to make it 7/8.
Pay two life to play Mutagenic Growth, again triggering the monk's prowess ability, to make your monk a 10/11 double strike trigger happy murderer.
Attack for 20 damage.

Life after turn one (for the not so lucky one)

Life after turn one continues to revolve around dealing 20+ damage with one or more critters. Try to have a critters out at turn one (either your Monastery Swiftspear or one of the two mana creatures, if you're packing a Simian Spirit Guide.
I'm getting quite consistent turn two/three kills with Kiln Fiend, who needs just two cards to give him double-strike and pump it up to deal 20+ damage. (Turn two kill requires you can play the Kiln Fiend on turn one, using a Simian Spirit Guide).
Note that having two 'prowerful' creatures on the table makes the pumping up part a whole lot more effective, as every instant or sorcery spell cast will trigger all creatures' prowess ability.
The deck requires very little mana; the cmc breaks down as follows (counting those spells that can be cast by paying life as '0'): 12 x 0, 20 x 1, 12 x 1, which makes the average cmc 1.2. This has the distinct advantage that it leaves a lot of room for more useful spells in the deck.
There's 8 spells that allow you to circumvent blockers: 4 copies each of Temur Battle Rage, which adds trample to your double-stiker, and Apostle's Blessing which allows your creature to run right past its colorful blockers.
The latter card also serves to protect your creature against whatever color card is out to hurt him/her.

Sideboard

The sideboard packs 7 cards for creature removal: (arranged from lighthearted to more drastic) Gut Shot, Dismember, Slaughter Pact.
I've added Summoning Trap to work around counterspells.
The Gitaxian Probes are there to sub into the mainboard in case your opponent isn't threatening your creatures as much as I expect they will.