Q1- Does Evilswarm is returned to hand?
Q2- Is Metaion effect negated?
Q3- Is Metaion destroyed as result of battle?
Q4- Is Metaion's player loses LP?
Can you explain the order of effects?
Just posting to expand upon L_Church's answer.
Let's look at the way Obliviwisp's effect is written:
After damage calculation, if this card battles a monster: Negate the effects of that monster (including in the Graveyard).
As this is an activated effect, and does not specify any window of time during which it applies, the effect applied is permanent. I.e, Metaion's effects are negated for the rest of the time it stays face up on the field, neglecting outside circumstances - and obviously this includes "At the end of the Battle Phase".
Note that Metaion can still activate its effects, just not apply them.
The important part to look at in Obliviwisp's effect here is "After damage calculation". During damage calculation, not only is the damage calculated and inflicted as necessary, but monsters are also "marked" for destruction (they haven't been destroyed yet at this point, but it is determined that they will be). Because Obliviwisp's effect does not activate until after this set of steps, the window of time in which Metaion could have been destroyed by that battle is missed.
For the same reason as in Question 3, Metaion's effect is not yet negated at the point where damage would be inflicted. Therefore, damage is not inflicted for that battle. Note that in subsequent battles, since Metaion's effects will have been negated by Obliviwisp, it would be destroyed, and damage would be inflicted.
Obliviwisp negates the effects of a monster after damage calc. Since Metaion effect to send back to the hand activates after Obliviwisp goes off you'd assume Metaion would be negated.
so for those questions,