knowledge - Piece de Resistance - King Deusovi, Flag this Blo*dy Post!

King Deusovi, Flag this Blo*dy Post!

_{This puzzle is part of the "Piece de Resistance" series. Go back to Part 1 (Ace) for the story.
Ace Two Three Four Five Six Seven Eight Nine Ten Queen King Jack}

Hmmm, what is this?

P.S.: word tag also applies.

Clarification:

The WHITE border of the image is NOT part of the puzzle.

Hint level 1:

ONLY the WHITE border of the image is NOT part of the puzzle. steganography only applies visually.

Answer

Title

From Title "flag this blo*ody post"
The colors blue and red remind me of two flags
- the Flag of Liechtenstein. The crown within could be referenced by the title word "king"...
- The Signal flag for E (ECHO)

Upper half (blue)

There are some hidden words: Ace ice oar Oman over

They are written upside down from right to left
Searching for a pattern, I tried adding letters forming new words:
Adding R gives Race, Rice, Roar, Roman, Rover

Lower half (red) Rebus:

First red square

- ace of spades - short A
- Elephant
- 3/4 of a cent - cent

-> Remove ent from Elephant -> lpha

Alpha

Second red square

- The land on the map is Tibet
- The lower left image is the logo of Texas Instruments - TI
- Ammeter - An instrument to measure the current (in Ampere)
-> Remove TI from Tibet -> bet
-> add A to bet
beta

Fourth red Square

- A 1915 Ford Model T
- A balloon flying with a child... must be filled with Helium, Chemical Symbol is He
- A Taxi
- An image of the chinese president Xi Jinping
Remove Xi from Taxi -> Ta

T He Ta -> Theta

Fifth red Square (Solved by JS1)

$P = V \times I$ (Formula of Electric power) and $I = \frac{V}{R}$
$=> \frac{V^3}{R^2} = \frac{V^2}{R} \times \frac{V}{R} = P \times I = PI$
Pi

Now back to the third square: (Solved by Stiv)

We have
1. $\alpha$ (Alpha, 1. Letter of the Greek Alphabet)
2. $\beta$ (Beta, 2. Letter of the Greek Alphabet)

3. ?
4. $\theta$ (Theta, 8. Letter of the Greek Alphabet)
5. $\pi$ (Pi, 16. Letter of the Greek Alphabet)
Now, it looks like the position of the letter is doubled in each square so the third should be
$\delta$ (Delta, 4. Letter)

Conclusion (thx to M Oehm & Stiv)

E from Echo-flag
R from the hidden words

D from 3. red square Delta
ERD anagrams to RED, fitting the bloody Hint from the title