Missing words after commas in these sentences?

Question

In the following sentence, why did they use "thinking" after the comma? Is a word omitted after the comma?

I waited for two months, thinking that it would be bad time for him.

Should it be something like "I waited for two months and now I am thinking that it would be bad time for him."?

In this sentence below (describing League of Legends), like I said above, is something like a word omitted after the comma? I just cannot figure out why they type something like this, I mean it seems more like a present continuous tense without "subject+be".

While Two-Shiv poison is not on cooldown, Shaco's basic attacks poison his targets, slowing them for 2 seconds and causing minions and monsters to ...

Answer 1

thinking that it would be bad time for him.
slowing them for 2 seconds and causing minions and monsters to

These are participle clauses acting as clausal supplements; and the -ing forms which head them are present participles (or active participles)

Internally, a participle takes the same dependents (subject, object, complements and modifiers) as other forms of the verb; but externally, in the sentence, the participle (with its dependents) plays the role of some other wordclass.

For instance, participle clauses can act as attributive adjectives, just like ordinary adjectives. If the participle has no following dependents, it may be placed before the noun it modifies; otherwise it is placed after the noun:

The quickly running child fell down.
The child running across the playground fell down.

In your examples, however, the participle clauses "modify" the entire main clause to which they are attached. The exact significance of that "modification" has to be inferred from the context.

• In the first, the missing subject of thinking is inferred to be the subject of the main clause I, and the participle clause expresses the motive for the action of the main clause: I waited because I thought it would be a bad time.

• In the second, the missing subject of slowing and causing is inferred to be the entire main clause, the action of poisoning, and the participle clause expresses the result of that action: poisoning the targets caused them to be slowed and caused minions and monsters to (something-or-other).

Note, by the way, that a clause headed by an active participle can also act as a noun; when that is the case we call the -ing form a gerund rather than a participle.

Slowing them for 2 seconds turned out to be a bad idea, because it gave their minions time to catch up with them.

Answer 2

The first sentence is correct. It has the meaning

I waited for two months, with the intent that [or being aware that] it would be a bad time for him.

In other words, it sounds like the speaker wanted it to be a bad time for "him", and so the speaker waited for two months, because the speaker believed such a wait would ensure that it was a "bad time".

The second sentence is also perfectly good usage. The part you're asking about could be rephrased as

...Shaco's basic attacks poison his targets, which slows them down for 2 seconds...

But the way it's written is simply a slightly more efficient way of saying the same thing.