Attested derivations are pwnage, skillage, and speakage.
The loose grammar, just like loose spelling, encodes some level of emphasis, ironic or otherwise.
A reader must rely more on intuitive parsing of leet to determine the meaning of a sentence rather than the actual sentence structure.
In particular, speakers of leet are fond of verbing nouns, turning verbs into nouns (and back again) as forms of emphasis, e.g. In essence, all of these mean "Austin rocks," not necessarily the other options.
Added words and misspellings add to the speaker's enjoyment.
Creative misspellings and ASCII-art-derived words were also a way to attempt to indicate one was knowledgeable about the culture of computer users.
Once the reserve of hackers, crackers, and script kiddies, leet has since entered the mainstream.
Nouns such as lulzness and leetness are derivations using this suffix. "This is the s&box," "I'm sorry, you've been b&", "&hill/&farm"). An alternate form of "B&" is "B7", as the ampersand is typed with the "7" key in the standard US keyboard layout.
When forming a past participle ending in -ed, the Leet user may replace the -e with an apostrophe, as was common in poetry of previous centuries, (e.g. It is often seen in the phrase "IBB7" (in before banned), which indicates that the poster believes that a previous poster will soon be banned from the site, channel, or board on which they are both posting.
For more casual use of leet, the primary strategy is to use homoglyphs, symbols that closely resemble (to varying degrees) the letters for which they stand.